def get(self, key, default=None):
        if key not in self:
            raise KeyError(
                'immutable %s %s schema does not contain key %r.' % (
                    type(self).__name__, self.name, key))
        # default will never be used.
        return self[key]
dataset/ETHPy150Open jek/flatland/flatland/schema/containers.py/Mapping.get/original