code: def project_activity(index, start, end):
      
  
      results = {
          "metrics": [SubmittedPRs(index, start, end),
                      ClosedPRs(index, start, end)]
      }
  
      return results
docs: Compute the metrics for the project activity section of the enriched
      github pull requests index.
  
      Returns a dictionary containing a "metric" key. This key contains the
      metrics for this section.
  
      :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