Helper function for creating MetricMetadata for gauge metrics.

def CreateGaugeMetadata(metric_name,
                        value_type,
                        fields=None,
                        docstring=None,
                        units=None):
  """Helper function for creating MetricMetadata for gauge metrics."""
  return rdf_stats.MetricMetadata(
      varname=metric_name,
      metric_type=rdf_stats.MetricMetadata.MetricType.GAUGE,
      value_type=MetricValueTypeFromPythonType(value_type),
      fields_defs=FieldDefinitionProtosFromTuples(fields or []),
      docstring=docstring,
      units=units)