'Returns problem_hparams.'

def internal_hparams(self, model_hparams):

    if (self._encoders is None):
        self.internal_build_encoders(model_hparams.data_dir)
    hp = _default_hparams()
    ret = self.hparams(hp, model_hparams)
    if (ret is not None):
        raise ValueError('The    Problem    subclass    hparams    function    should    mutate    the    defaults    passed    in    and    return    None.')
    hp.add_hparam('vocabulary', self._encoders)
    hp.add_hparam('was_reversed', self._was_reversed)
    hp.add_hparam('was_copy', self._was_copy)
    if self._was_reversed:
        _reverse_problem_hparams(hp)
    if self._was_copy:
        _copy_problem_hparams(hp)
    return hp
