code: def gpib_command(self, session, command_byte):
          
          try:
              return self.sessions[session].gpib_command(command_byte)
  
          except KeyError:
              return constants.StatusCode.error_invalid_object
docs: Write GPIB command byte on the bus.
  
          Corresponds to viGpibCommand function of the VISA library.
          See: https://linux-gpib.sourceforge.io/doc_html/gpib-protocol.html#REFERENCE-COMMAND-BYTES
  
          :param command_byte: command byte to send
          :type command_byte: int, must be [0 255]
          :return: return value of the library call
          :rtype: :class:`pyvisa.constants.StatusCode`