docs: def get_arctic_lib(connection_string, **kwargs):
      """
      Returns a mongo library for the given connection string
  
      Parameters
      ---------
      connection_string: `str`
          Format must be one of the following:
              library@trading for known mongo servers
              library@hostname:port
  
      Returns:
      --------
      Arctic library
      """
      m = CONNECTION_STR.match(connection_string)
      if not m:
          raise ValueError("connection string incorrectly formed: %s" % connection_string)
      library, host = m.group(1), m.group(2)
      return _get_arctic(host, **kwargs)[library]