docs: def overview(index, start, end):
      """Compute metrics in the overview section for enriched git indexes.
  
      Returns a dictionary. Each key in the dictionary is the name of
      a metric, the value is the value of that metric. Value can be
      a complex object (eg, a time series).
  
      :param index: index object
      :param start: start date to get the data from
      :param end: end date to get the data upto
      :return: dictionary with the value of the metrics
      """
  
      results = {
          "activity_metrics": [Commits(index, start, end)],
          "author_metrics": [Authors(index, start, end)],
          "bmi_metrics": [],
          "time_to_close_metrics": [],
          "projects_metrics": []
      }
  
      return results