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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _make_bridge_request_msg(self, channel, netfn, command):
 """This function generate message for bridge request. It is a part of ipmi payload. """

        head = bytearray((constants.IPMI_BMC_ADDRESS,
                          constants.netfn_codes['application'] << 2))
        check_sum = _checksum(*head)
        # NOTE(fengqian): according IPMI Figure 14-11, rqSWID is set to 81h
        boday = bytearray((0x81, self.seqlun, constants.IPMI_SEND_MESSAGE_CMD,
                           0x40 | channel))
        # NOTE(fengqian): Track request
        self._add_request_entry((constants.netfn_codes['application'] + 1,
                                 self.seqlun, constants.IPMI_SEND_MESSAGE_CMD))
        return head + bytearray((check_sum,)) + boday