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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 _ssh_build_mic(self, session_id, username, service, auth_method):
 """ Create the SSH2 MIC filed for gssapi-with-mic. :param str session_id: The SSH session ID :param str username: The name of the user who attempts to login :param str service: The requested SSH service :param str auth_method: The requested SSH authentication mechanism :return: The MIC as defined in RFC 4462. The contents of the MIC field are: string session_identifier, byte SSH_MSG_USERAUTH_REQUEST, string user-name, string service (ssh-connection), string authentication-method (gssapi-with-mic or gssapi-keyex) """

        mic = self._make_uint32(len(session_id))
        mic += session_id
        mic += struct.pack("B", MSG_USERAUTH_REQUEST)
        mic += self._make_uint32(len(username))
        mic += username.encode()
        mic += self._make_uint32(len(service))
        mic += service.encode()
        mic += self._make_uint32(len(auth_method))
        mic += auth_method.encode()
        return mic