How to use the icontract._represent.generate_message function in icontract

missing_args = [arg_name for arg_name in contract.error_args if arg_name not in resolved_kwargs]
            if missing_args:
                msg_parts = []
                if contract.location is not None:
                    msg_parts.append("{}:\n".format(contract.location))

                msg_parts.append(
                    ("The argument(s) of the precondition error have not been set: {}. "
                     "Does the original function define them? Did you supply them in the call?").format(missing_args))

                raise TypeError(''.join(msg_parts))

            raise contract.error(**error_kwargs)

        else:
            msg = icontract._represent.generate_message(contract=contract, condition_kwargs=condition_kwargs)
            if contract.error is None:
                raise ViolationError(msg)
            elif isinstance(contract.error, type):
                raise contract.error(msg)

check = contract.condition(self=instance)
    else:
        check = contract.condition()

    if _not_check(check=check, contract=contract):
        if contract.error is not None and (inspect.ismethod(contract.error) or inspect.isfunction(contract.error)):
            assert contract.error_arg_set is not None, "Expected error_arg_set non-None if contract.error a function."
            assert contract.error_args is not None, "Expected error_args non-None if contract.error a function."

            if 'self' in contract.error_arg_set:
                raise contract.error(self=instance)
            else:
                raise contract.error()
        else:
            if 'self' in contract.condition_arg_set:
                msg = icontract._represent.generate_message(contract=contract, condition_kwargs={"self": instance})
            else:
                msg = icontract._represent.generate_message(contract=contract, condition_kwargs=dict())

            if contract.error is None:
                raise ViolationError(msg)
            elif isinstance(contract.error, type):
                raise contract.error(msg)
            else:
                raise NotImplementedError("Unhandled contract.error: {}".format(contract.error))

missing_args = [arg_name for arg_name in contract.error_args if arg_name not in resolved_kwargs]
            if missing_args:
                msg_parts = []
                if contract.location is not None:
                    msg_parts.append("{}:\n".format(contract.location))

                msg_parts.append(
                    ("The argument(s) of the postcondition error have not been set: {}. "
                     "Does the original function define them? Did you supply them in the call?").format(missing_args))

                raise TypeError(''.join(msg_parts))

            raise contract.error(**error_kwargs)

        else:
            msg = icontract._represent.generate_message(contract=contract, condition_kwargs=condition_kwargs)
            if contract.error is None:
                raise ViolationError(msg)
            elif isinstance(contract.error, type):
                raise contract.error(msg)