Returns human readable submission external ID.

    Args:
      submission_id: internal submission ID.

    Returns:
      human readable ID.

def get_external_id(self, submission_id):
    """Returns human readable submission external ID.

    Args:
      submission_id: internal submission ID.

    Returns:
      human readable ID.
    """
    submission = self.find_by_id(submission_id)
    if not submission:
      return None
    if 'team_id' in submission.participant_id:
      return submission.participant_id['team_id']
    elif 'baseline_id' in submission.participant_id:
      return 'baseline_' + submission.participant_id['baseline_id']
    else:
      return ''