docs: def WriteGraphSeries(graph_series,
                       label,
                       token = None):
    """Writes graph series for a particular client label to the DB.
  
    Args:
      graph_series: A series of rdf_stats.Graphs containing aggregated data for a
        particular report-type.
      label: Client label by which data in the graph_series was aggregated.
      token: ACL token to use for writing to the legacy (non-relational)
        datastore.
  
    Raises:
      AFF4AttributeTypeError: If, when writing to the legacy DB, an unexpected
      report-data type is encountered.
    """
    if data_store.RelationalDBEnabled():
      data_store.REL_DB.WriteClientGraphSeries(graph_series, label)
  
    if _ShouldUseLegacyDatastore():
      # We need to use the __call__() method of the aff4.Attribute class
      # to instantiate Graph and GraphSeries objects, or AFF4Object.AddAttribute()
      # won't work.
      aff4_attr = _GetAFF4AttributeForReportType(graph_series.report_type)()
  
      if isinstance(aff4_attr, rdf_stats.GraphSeries):
        for graph in graph_series.graphs:
          aff4_attr.Append(graph)
      elif isinstance(aff4_attr, rdf_stats.Graph):
        for sample in graph_series.graphs[0]:
          aff4_attr.Append(x_value=sample.x_value, y_value=sample.y_value)
      else:
        raise AFF4AttributeTypeError(aff4_attr.__class__)
  
      with aff4.FACTORY.Create(
          GetAFF4ClientReportsURN().Add(label),
          aff4_type=aff4_stats.ClientFleetStats,
          mode="w",
          token=token) as stats_for_label:
        stats_for_label.AddAttribute(aff4_attr)