code: def create_header(cls, request_id=None):
          ''' Return a message header fragment dict.
  
          Args:
              request_id (str or None) :
                  Message ID of the message this message replies to
  
          Returns:
              dict : a message header
  
          '''
          header = {
              'msgid'   : bkserial.make_id(),
              'msgtype' : cls.msgtype
          }
          if request_id is not None:
              header['reqid'] = request_id
          return headef create_header(cls, request_id=None):
          ''' Return a message header fragment dict.
  
          Args:
              request_id (str or None) :
                  Message ID of the message this message replies to
  
          Returns:
              dict : a message header
  
          '''
          header = {
              'msgid'   : bkserial.make_id(),
              'msgtype' : cls.msgtype
          }
          if request_id is not None:
              header['reqid'] = request_id
          return header
docs: Return a message header fragment dict.
  
          Args:
              request_id (str or None) :
                  Message ID of the message this message replies to
  
          Returns:
              dict : a message header