'In-place difference with *other* set.'

def difference(self, other):

    context = self._context
    builder = self._builder
    payload = self.payload
    other_payload = other.payload
    with other_payload._iterate() as loop:
        entry = loop.entry
        self._remove_key(payload, entry.key, entry.hash, do_resize=False)
    self.downsize(payload.used)
