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Why Science? | European Variation Archive Variant and Study Evidence

Three students sit around open books and worksheets at a classroom table, reading, writing and discussing the work together.

eduKateSG · Why Science?

Follow a genetic variant from submitted study to comparable record

A careful guide to EVA studies, VCF files, SS and RS accessions, normalisation, allele frequency and consequence annotations for evidence-aware genomics learning.

Full chapter index · Science Learning Hub

A genetic variant may be written as a short change in sequence, yet its meaning depends on the reference assembly, study, samples, representation and evidence. The European Variation Archive, or EVA, makes these layers inspectable through an open archive for genetic variation data from many species.

EVA accepts precise variants represented in VCF, provides study and variant browsing, and exposes data through downloads and an API. Its official help explains that submitted variants are normalised, non-human variants can receive SS and RS accessions, human variant identifiers are coordinated with NCBI resources, and consequence annotations use Ensembl VEP where supported.

Did you know? Two VCF descriptions can refer to the same underlying change but place or represent it differently around repeated sequence. Normalisation helps create a comparable representation. That processing step is a wonderful science-learning example: data cleaning is not cosmetic when coordinates and alleles define the object being compared.

This article keeps four questions visible. What study supplied the variant? Which reference assembly and alleles define it? What processing or annotation was applied? What claim remains justified after frequency, population and evidence limits are stated?

CHAPTER 1 OF 17 · Open the study

1. EVA is a primary variation archive

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Start with the record itself, because a good science explanation names the object before interpreting it. EVA describes itself as an open-access database for genetic variation data from all species and a primary deposition archive for precise variants. Users can search studies and variants, download data and access programmatic services. For secondary science learning, that distinction turns database browsing into evidence practice rather than fact collecting.

Try this

Ask: Is the page showing an archived study, an individual variant, an accession release or a derived annotation? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Open the EVA home page and classify each main route by the evidence object it is designed to expose. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. Do not fill a blank with a guess. Record the missing field, follow the linked accession or method, and state exactly what remains uncertain. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the eva is a primary variation archive evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Next chapter

CHAPTER 2 OF 17 · Open the study

2. Projects organise submitted studies

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Here the useful move is to separate what the archive stores from what a researcher may later infer. EVA administers project accessions beginning PRJEB for submitted projects. A project record groups variation files, metadata and related analysis objects, providing study context before a reader inspects individual variants. It also connects classroom habits—defining variables, tracing methods and comparing like with like—to real research infrastructure.

Try this

Ask: Which project accession, title and species or cohort context belong together? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Record one project accession and make a list of every linked object type without treating those objects as interchangeable. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. Keep observation and interpretation in separate sentences. That simple discipline makes the reasoning easier to audit and revise. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the projects organise submitted studies evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 3 OF 17 · Open the study

3. Analysis accessions identify archived objects

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This part of the record rewards slow reading: labels, identifiers and relationships do different jobs. EVA help states that analysis objects receive ERZ accessions after data are validated and archived. These stable identifiers can be cited and linked to files within the project. The same habit matters beyond school: technicians, analysts, curators and researchers all need to know which layer of a record supports a statement.

Try this

Ask: Which ERZ object is connected to the project, and what file or processing role does it represent? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Follow an analysis link and describe its relationship to the project in one precise sentence. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. Compare records only after checking that their organisms, samples, methods, reference versions and study questions are compatible. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the analysis accessions identify archived objects evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 4 OF 17 · Open the study

4. VCF structures variation records

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A cheerful surprise in data science is that careful organisation can make a complicated investigation much easier to understand. EVA requires genetic variants to be described in valid Variant Call Format files matched to a registered reference sequence. VCF separates coordinate and allele fields from INFO and sample FORMAT fields. This is a practical lesson in scientific literacy because structured data can look authoritative even when an essential qualifier is missing.

Try this

Ask: Which assembly, chromosome or contig, position, reference allele and alternate allele define the record? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Read one VCF-like row or variant display and label each core identity field before looking at consequences. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. A database result is a route into evidence, not a verdict. Preserve the accession, date and filters so another reader can retrace the route. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the vcf structures variation records evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 5 OF 17 · Identify the variant

5. Reference assemblies are part of identity

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Treat this as a small evidence puzzle. The visible fields tell you what can be checked and what still needs another source. A coordinate only has meaning against a particular reference assembly and sequence naming system. EVA requires reference sequences to be registered or registered at submission, helping preserve that context. Reading the field in context helps a learner explain both the useful signal and the limit of the claim.

Try this

Ask: Which assembly version anchors this position, and would the same coordinate mean the same thing on another assembly? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Write a variant identifier card that includes assembly, sequence, position, reference and alternate alleles. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. When the interface changes, the stable identifier and source documentation matter more than the position of a button on the page. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the reference assemblies are part of identity evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 6 OF 17 · Identify the variant

6. Normalisation improves comparison

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Start with the record itself, because a good science explanation names the object before interpreting it. EVA explains that variants are normalised because different callers can describe changes differently. Its processing left-aligns variants and sets start and end positions to the exact changed range, including special handling for insertions. For secondary science learning, that distinction turns database browsing into evidence practice rather than fact collecting.

Try this

Ask: Was the displayed representation submitted directly or produced after normalisation? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Create two equivalent-looking indel descriptions in a toy repeat and discuss why a canonical rule helps matching. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. Do not fill a blank with a guess. Record the missing field, follow the linked accession or method, and state exactly what remains uncertain. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the normalisation improves comparison evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 7 OF 17 · Identify the variant

7. SS and RS accessions have different roles

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Here the useful move is to separate what the archive stores from what a researcher may later infer. Submitted SNP identifiers, or SS accessions, represent submitted variant observations, while reference SNP identifiers, or RS accessions, cluster equivalent variants under reference contexts. EVA follows accessioning principles coordinated with dbSNP. It also connects classroom habits—defining variables, tracing methods and comparing like with like—to real research infrastructure.

Try this

Ask: Is this identifier tied to a submission or to a clustered reference variant? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Put SS and RS on separate cards and connect them with an arrow labelled “may be clustered into” rather than “is identical to”. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. Keep observation and interpretation in separate sentences. That simple discipline makes the reasoning easier to audit and revise. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the ss and rs accessions have different roles evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 8 OF 17 · Identify the variant

8. Human and non-human routes differ

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This part of the record rewards slow reading: labels, identifiers and relationships do different jobs. EVA accessions non-human variants and exchanges human variation data with NCBI dbSNP and dbVar. The archive can still expose human study data and returned identifiers, but the accessioning route differs by species. The same habit matters beyond school: technicians, analysts, curators and researchers all need to know which layer of a record supports a statement.

Try this

Ask: Who administers the accession for this species and variant type? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Compare the official routing statements for a human and a non-human variant without generalising one workflow to all species. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. Compare records only after checking that their organisms, samples, methods, reference versions and study questions are compatible. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the human and non-human routes differ evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 9 OF 17 · Read processing context

9. Study Browser preserves submitted context

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A cheerful surprise in data science is that careful organisation can make a complicated investigation much easier to understand. The Study Browser provides access to project information and submitted VCF files. Raw submitted files remain important because they preserve the form and metadata supplied by the depositor. This is a practical lesson in scientific literacy because structured data can look authoritative even when an essential qualifier is missing.

Try this

Ask: Which file is original submission evidence, and which file is prepared for browsing or accession release? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: List the available file categories for one study and state which you would use to audit the submitted representation. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. A database result is a route into evidence, not a verdict. Preserve the accession, date and filters so another reader can retrace the route. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the study browser preserves submitted context evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 10 OF 17 · Read processing context

10. Variant Browser supports targeted queries

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Treat this as a small evidence puzzle. The visible fields tell you what can be checked and what still needs another source. The Variant Browser can query loaded variants by study, gene, chromosomal location or identifiers. Query results are a view over processed data and should retain the filters and assembly context used. Reading the field in context helps a learner explain both the useful signal and the limit of the claim.

Try this

Ask: What query created this result set, and which loaded studies or variants might sit outside it? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Run a narrow query, save its parameters, and explain why a browser result count is not the number of affected people. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. When the interface changes, the stable identifier and source documentation matter more than the position of a button on the page. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the variant browser supports targeted queries evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 11 OF 17 · Read processing context

11. Allele frequency is study-specific

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Start with the record itself, because a good science explanation names the object before interpreting it. EVA states that allele frequency values are study specific. With genotype data it can calculate AF as alternate allele observations divided by total allele observations; otherwise it may use submitted AF or calculate from AC and AN fields. For secondary science learning, that distinction turns database browsing into evidence practice rather than fact collecting.

Try this

Ask: Which study, population, numerator and denominator support the frequency shown? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Given AC and AN toy values, calculate AF and then explain why the result cannot be transferred automatically to another population. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. Do not fill a blank with a guess. Record the missing field, follow the linked accession or method, and state exactly what remains uncertain. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the allele frequency is study-specific evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 12 OF 17 · Read processing context

12. Population labels need sample context

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Here the useful move is to separate what the archive stores from what a researcher may later infer. Within-study population or cohort frequencies depend on structured sample information and study design. A group label alone does not establish representativeness, ancestry, health status or independence of observations. It also connects classroom habits—defining variables, tracing methods and comparing like with like—to real research infrastructure.

Try this

Ask: How was the population defined, and how many samples or allele observations contribute? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Build a frequency note that includes study accession, population label, AC, AN and a warning about generalisation. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. Keep observation and interpretation in separate sentences. That simple discipline makes the reasoning easier to audit and revise. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the population labels need sample context evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 13 OF 17 · Judge the claim

13. Consequence annotations are predictions

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This part of the record rewards slow reading: labels, identifiers and relationships do different jobs. After normalisation, EVA uses Ensembl Variant Effect Predictor where supported and describes consequences with Sequence Ontology terms. A predicted consequence labels a relationship to transcripts or genomic features; it is not direct proof of phenotype or disease. The same habit matters beyond school: technicians, analysts, curators and researchers all need to know which layer of a record supports a statement.

Try this

Ask: Which transcript, gene build, VEP version and consequence term produced the annotation? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Turn “this variant causes” into a transcript-aware statement about the predicted consequence and name the evidence still required. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. Compare records only after checking that their organisms, samples, methods, reference versions and study questions are compatible. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the consequence annotations are predictions evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 14 OF 17 · Judge the claim

14. Some records lack annotations or frequencies

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A cheerful surprise in data science is that careful organisation can make a complicated investigation much easier to understand. Official help notes that annotation depends on Ensembl support and that some submitted variants may lack enough genotype or summary fields for frequency calculation. Missing output is therefore an evidence condition, not permission to invent a value. This is a practical lesson in scientific literacy because structured data can look authoritative even when an essential qualifier is missing.

Try this

Ask: Is the field absent because of unsupported reference context, unavailable inputs, processing status or another stated reason? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Make a missing-data decision tree and end each branch with the next source to inspect. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. A database result is a route into evidence, not a verdict. Preserve the accession, date and filters so another reader can retrace the route. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the some records lack annotations or frequencies evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 15 OF 17 · Judge the claim

15. APIs and downloads support reproducibility

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Treat this as a small evidence puzzle. The visible fields tell you what can be checked and what still needs another source. EVA exposes loaded data through an API and provides study or release downloads. Programmatic access helps repeat searches, but software must still record endpoint, parameters, release or retrieval date and assembly. Reading the field in context helps a learner explain both the useful signal and the limit of the claim.

Try this

Ask: Which endpoint or download represents the needed evidence layer, and is it current or release-specific? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Write a small request log with URL, parameters, timestamp and expected object type, then check the response before analysis. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. When the interface changes, the stable identifier and source documentation matter more than the position of a button on the page. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the apis and downloads support reproducibility evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 16 OF 17 · Judge the claim

16. Open access has ethical boundaries

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Start with the record itself, because a good science explanation names the object before interpreting it. EVA is an open archive and submitters must ensure data can be shared under its policy. Open availability does not justify attempts to identify individuals, overstate medical meaning or ignore consent and cohort context. For secondary science learning, that distinction turns database browsing into evidence practice rather than fact collecting.

Try this

Ask: What use is technically possible, what use is scientifically justified, and what use would be ethically inappropriate? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Draft a responsible classroom rule for human variant data that permits evidence learning while preventing personal inference. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. Do not fill a blank with a guess. Record the missing field, follow the linked accession or method, and state exactly what remains uncertain. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the open access has ethical boundaries evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Next chapter

CHAPTER 17 OF 17 · Judge the claim

17. Variant literacy connects science careers

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Here the useful move is to separate what the archive stores from what a researcher may later infer. Genomics laboratories, archive teams, clinical scientists, breeders, conservation researchers, software developers and data stewards all need consistent variant representation. The shared skill is tracing a claim through identifiers, reference context and evidence type. It also connects classroom habits—defining variables, tracing methods and comparing like with like—to real research infrastructure.

Try this

Ask: Which professional decision could fail if assembly, allele or accession context were lost? Write the answer as a claim-evidence-reasoning note. Quote no more than the field needs; instead, paraphrase the record, name the accession or object type, and explain why that field is relevant. If two pages disagree, check their update context and follow the primary documentation before deciding that one is wrong.

Try this: Choose one career and write a handover checklist for a variant record that another professional could safely continue. Then add one sentence beginning ‘This record can support…’ and another beginning ‘This record cannot by itself establish…’. Keep observation and interpretation in separate sentences. That simple discipline makes the reasoning easier to audit and revise. That two-sentence finish keeps the activity optimistic, precise and honest.

Evidence checkpoint

Name the variant literacy connects science careers evidence you used, keep its identifier or field label visible, and state one limit before moving on.

Contents · Previous chapter · Continue at the Science Learning Hub

A variant is small; its evidence context is not

EVA turns a compact sequence change into an inspectable route through project, file, assembly, accession, normalisation, frequency and annotation. Keeping those layers visible prevents a coordinate or consequence label from carrying more meaning than the evidence allows.

For students, the positive lesson is simple: precision creates possibilities. A well-recorded variant can be compared, reanalysed and connected across resources, while careful limits keep the comparison scientifically useful.

Reading objectWhat it can supportQuestion to keep visible
Project or analysis accessionStable route to study-level objectsWhich files and samples are linked?
Variant coordinates and allelesDefines the change on a reference assemblyWhich assembly and sequence are required?
SS or RS accessionTracks submitted or clustered variant identityWhat accessioning role applies?
Frequency or consequenceStudy-specific statistic or annotationWhich population, inputs and version support it?
Keep every variant statement attached to reference, study and processing context.

Sources and next reading

Substantive resource claims in this article were checked against the primary pages below. A database record is a structured route into evidence; it does not by itself prove a new biological conclusion. Recheck the live record, evidence labels and release context before using it in assessed work or research.

Primary sources

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