code: def _ClientIDFromSessionID(session_id):
    
  
    parts = session_id.Split(4)
    client_id = parts[0]
    if re.match(r"C\.[0-9a-f]{16}", client_id):
      return client_id
  
    # Maybe it's a legacy hunt id (aff4:/hunts/<hunt_id>/<client_id>/...
    client_id = parts[2]
    if re.match(r"C\.[0-9a-f]{16}", client_id):
      return client_id
  
    raise ValueError("Unable to parse client id from session_id: %s" % session_id)
docs: Extracts the client id from a session id.