Fix type mismatch.

  // TODO: use a structure with fast (log N?) removal/insertion and random access.

  // Or sample randomly from std::unordered_set using its hash function, if it's good enough.

  std::vector<const std::vector<unsigned long long>*> partners_lists_;

  std::vector<const std::vector<std::uint64_t>*> partners_lists_;

  unsigned short last_insertion_size_ = 1;

  const double max_tau_ = 0;

  const int n_bands_ = 0;