'Combines the national number with any prefix (IDD/+ and country
code or national prefix) that was collected. A space will be inserted
between them if the current formatting template indicates this to be
suitable.'

def _append_national_number(self, national_number):

    prefix_before_nn_len = len(self._prefix_before_national_number)
    if (self._should_add_space_after_national_prefix and (prefix_before_nn_len > 0) and (self._prefix_before_national_number[(-1)] != _SEPARATOR_BEFORE_NATIONAL_NUMBER)):
        return ((self._prefix_before_national_number + _SEPARATOR_BEFORE_NATIONAL_NUMBER) + national_number)
    else:
        return (self._prefix_before_national_number + national_number)
