docs: def _make_chunk_size(self, req_size):
          """
          Takes an allocation size as requested by the user and modifies it to be a suitable chunk size.
          """
          size = req_size
          size += 2 * self._chunk_size_t_size  # Two size fields
          size = self._chunk_min_size if size < self._chunk_min_size else size
          if size & self._chunk_align_mask:                                         # If the chunk would not be aligned
              size = (size & ~self._chunk_align_mask) + self._chunk_align_mask + 1  # Fix it
          return size