namespace lasd {

template <typename Data>
void AuxFoldExists(const Data& dat, const void* val, void* exists){
  if(dat == *((Data*)val)){
    *((bool*)exists) = true;
  }
}

template <typename Data>
bool FoldableContainer<Data>::Exists(const Data& dat) const noexcept{
  bool exists = false;
  FoldPreOrder(&AuxFoldExists<Data>, &dat, &exists);
  return exists;
}

}