def group_by(self, func):
        return self._transform(transformations.group_by_t(func))
store nick, user, host in kwargs if prefix is correct format
dataset/ETHPy150Open EntilZha/PyFunctional/functional/pipeline.py/Sequence.group_by--crossover with--dataset/ETHPy150Open numberoverzero/bottom/bottom/unpack.py/nickmask