def _cut_grpos(self):
        d = self._s.data
        target_grpos = self._grpos_last - self._buffer_grpos
        pos, grpos, l = 0, self._grpos_first, len(d)
        while grpos < target_grpos and pos < l:
            pos += 1
            grpos = d[pos][0]
        if pos > 0:
            self._s.data_offset, d[:pos] = self._s.data_offset - pos, []
            self._grpos_first = d[0][0]
dataset/ETHPy150Open arkadini/twimp/twimp/server/inmemory.py/IMLiveStream._cut_grpos/operator `+` -> `-`