StringPiece KeyedDenseTensorColumn<StringPiece>::Feature(
    int64 batch, int64 n, bool strong_hash) const {
  return tensor_.matrix<tstring>()(batch, n);
}
StringPiece KeyedDenseTensorColumn<StringPiece>::Feature(
    int64 batch, int64 n, bool strong_hash) const {
  return tensor_.matrix<tstring>()(batch, n);
}