code: def __x_google_quota_definitions_descriptor(self, limit_definitions):
      
      if not limit_definitions:
        return None
  
      definitions_list = [{
          'name': ld.metric_name,
          'metric': ld.metric_name,
          'unit': '1/min/{project}',
          'values': {'STANDARD': ld.default_limit},
          'displayName': ld.display_name,
      } for ld in limit_definitions]
  
      metrics = [{
          'name': ld.metric_name,
          'valueType': 'INT64',
          'metricKind': 'GAUGE',
      } for ld in limit_definitions]
  
      return {
          'quota': {'limits': definitions_list},
          'metrics': metrics,
      }
docs: Describes the quota limit definitions for an API.
  
      Args:
        limit_definitions: List of endpoints.LimitDefinition tuples
  
      Returns:
        A dict descriptor of the API's quota limit definitions.