code: def iter_entries(self):
          
          for idx in range(self._entry_count):
              dir_entry_offset = self._offset + 2 + (idx*12)
              ifd_entry = _IfdEntryFactory(self._stream_rdr, dir_entry_offset)
              yield ifd_entry
docs: Generate an |_IfdEntry| instance corresponding to each entry in the
          directory.