def observe(self, obj, formatter=lambda x: x._repr()):
        key = self._key(obj)
        if key not in self.formatted:
            self.aliases[key] = 'ref_%d' % len(self.formatted)
            self.formatted[key] = formatter(obj)
            self.ops[key] = obj

        self.counts[key] += 1
dataset/ETHPy150Open cloudera/ibis/ibis/expr/format.py/FormatMemo.observe/original