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Given the following text description, write Python code to implement the functionality described below step by step
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Description:
 Method Overview
gc.searchDatasets() -- Returns an iterator over the Datasets on the server.
gc.searchVariantSets(datasetId) -- Returns an iterator over the VariantSets fulfilling the specified conditions from the specified Dataset.
gc.searchCallSets(variantSetId, name=None) -- Returns an iterator over the CallSets for variantSetId
gc.searchVariants(variantSetId, start=None, end=None, referenceName=None, callSetIds=None) -- Returns an iterator over the Variants fulfilling the specified conditions from the specified VariantSet.
gc.searchVariantAnnotationSets(variantSetId) -- Returns an iterator over the AnnotationSets fulfilling the specified conditions from the specified Dataset.
gc.searchVariantAnnotations(variantAnnotationSetId, referenceName=None, referenceId=None, start=None, end=None, featureIds=[], effects=[]) -- Returns an iterator over the Annotations fulfilling the specified conditions from the specified AnnotationSet.
Step1:  Fetch Data Sets
Step2:  Variant Sets for each Data Set (currently only one)
Step3:  Call Sets (by variant set)
Step4:  Variant Annotation Sets (by variant set)
Step5:  Variant Annotations (by variant set and region)
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Python Code:
import pandas as pd
import ga4gh.client
print(ga4gh.__version__)
gc = ga4gh.client.HttpClient("http://localhost:8000")
region_constraints = dict(referenceName="1", start=0, end=int(1e10))
Explanation: Method Overview
gc.searchDatasets() -- Returns an iterator over the Datasets on the server.
gc.searchVariantSets(datasetId) -- Returns an iterator over the VariantSets fulfilling the specified conditions from the specified Dataset.
gc.searchCallSets(variantSetId, name=None) -- Returns an iterator over the CallSets for variantSetId
gc.searchVariants(variantSetId, start=None, end=None, referenceName=None, callSetIds=None) -- Returns an iterator over the Variants fulfilling the specified conditions from the specified VariantSet.
gc.searchVariantAnnotationSets(variantSetId) -- Returns an iterator over the AnnotationSets fulfilling the specified conditions from the specified Dataset.
gc.searchVariantAnnotations(variantAnnotationSetId, referenceName=None, referenceId=None, start=None, end=None, featureIds=[], effects=[]) -- Returns an iterator over the Annotations fulfilling the specified conditions from the specified AnnotationSet.
End of explanation
data_sets = pd.DataFrame(ds.toJsonDict() for ds in gc.searchDatasets())
data_sets.head()
Explanation: Fetch Data Sets
End of explanation
variant_sets = pd.DataFrame([
    {'data_set_id': ds.id,
     'variant_set_id': vs.id,
     'variant_set_name': vs.name}
    for ds in gc.searchDatasets()
    for vs in gc.searchVariantSets(ds.id)
    ])
variant_sets.head()
Explanation: Variant Sets for each Data Set (currently only one)
End of explanation
call_sets = pd.DataFrame([
    {
     'data_set_id': ds.id,
     'variant_set_id': vs.id,
     'variant_set_name': vs.name,
     'call_set_id': cs.id,
     'call_set_name': cs.name,
    }
    for ds in gc.searchDatasets()
    for vs in gc.searchVariantSets(ds.id)
    for cs in gc.searchCallSets(vs.id)
    ])
call_sets.head()
Explanation: Call Sets (by variant set)
End of explanation
call_sets = pd.DataFrame([
    {
     'data_set_id': ds.id,
     'variant_set_id': vs.id,
     'variant_set_name': vs.name,
     'variant_annotation_set_id': vas.id,
     'variant_annotation_set_name': vas.name,
    }
    for ds in gc.searchDatasets()
    for vs in gc.searchVariantSets(ds.id)
    for vas in gc.searchVariantAnnotationSets(vs.id)
    ])
call_sets.head()
Explanation: Variant Annotation Sets (by variant set)
End of explanation
call_sets = pd.DataFrame([
    {
     'data_set_id': ds.id,
     'variant_set_id': vs.id,
     'variant_set_name': vs.name,
     'n_callsets': sum(w for _ in gc.searchCallSets(vs.id)),
     'n_variants': sum(1 for _ in gc.searchVariants(vs.id, **region_constraints)),
     'n_annotation_sets': sum(1 for _ in gc.searchVariantAnnotationSets(vs.id)),
     'n_annotations': sum(1
                          for vas in gc.searchVariantAnnotationSets(vs.id)
                          for _ in gc.searchVariantAnnotations(vas.id, **region_constraints)
                         ),           
    }
    for ds in gc.searchDatasets()
    for vs in gc.searchVariantSets(ds.id)
    for vas in gc.searchVariantAnnotationSets(vs.id)
    ])
call_sets.head()
Explanation: Variant Annotations (by variant set and region)
End of explanation
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