Internal function to invoke the actual submit_single function
        :param iterobj: The raw object returned as the next item of the iterator
        :param is_dict: True if iterator is a dictionary
        :param is_itmcoll: True if the iterator contains Item objects
        :param mres: The multi result object
        :param global_kw: The global settings
        :return: The return value of :meth:`submit_single`

def _invoke_submit(self, iterobj, is_dict, is_itmcoll, mres, global_kw):
        """
        Internal function to invoke the actual submit_single function
        :param iterobj: The raw object returned as the next item of the iterator
        :param is_dict: True if iterator is a dictionary
        :param is_itmcoll: True if the iterator contains Item objects
        :param mres: The multi result object
        :param global_kw: The global settings
        :return: The return value of :meth:`submit_single`
        """
        if is_itmcoll:
            item, key_options = next(iterobj)
            key = item.key
            value = item.value
            result = item
        else:
            if is_dict:
                key, value = next(iterobj)
                if not self.VALUES_ALLOWED and not is_itmcoll:
                    raise ArgumentError.pyexc(
                        'Values not allowed for this command', obj=value)
            else:
                key = next(iterobj)
                value = None

            key_options = {}
            item = None
            result = self.make_result(key, value)

        result.rc = -1

        # Attempt to get the encoded key:
        key, value, key_options = self.make_entry_params(key, value, key_options)
        c_key, c_len = create_key(self.parent._tc, key)

        rc = self.submit_single(c_key, c_len, value, item, key_options, global_kw, mres)
        if rc:
            raise pycbc_exc_lcb(rc)
        try:
            if key in mres and not self.DUPKEY_OK:
                # For tests:
                self.parent._warn_dupkey(key)

            mres[key] = result
        except TypeError:
            raise pycbc_exc_enc(obj=key)