Generate an |_IfdEntry| instance corresponding to each entry in the
        directory.

def iter_entries(self):
        """
        Generate an |_IfdEntry| instance corresponding to each entry in the
        directory.
        """
        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