code: def participant_from_submission_path(submission_path):
    
    basename = os.path.basename(submission_path)
    file_ext = None
    for e in ALLOWED_EXTENSIONS:
      if basename.endswith(e):
        file_ext = e
        break
    if not file_ext:
      raise ValueError('Invalid submission path: ' + submission_path)
    basename = basename[:-len(file_ext)]
    if basename.isdigit():
      return {'team_id': int(basename)}
    if basename.startswith('baseline_'):
      return {'baseline_id': basename[len('baseline_'):]}
    raise ValueError('Invalid submission path: ' + submission_path)
docs: Parses type of participant based on submission filename.
  
    Args:
      submission_path: path to the submission in Google Cloud Storage
  
    Returns:
      dict with one element. Element key correspond to type of participant
      (team, baseline), element value is ID of the participant.
  
    Raises:
      ValueError: is participant can't be determined based on submission path.