@property<EOL><INDENT>def is_distinct(self):<DEDENT>
return bool(self.__group_by and<EOL>set(self._to_property_names(self.__group_by)) <=<EOL>set(self._to_property_names(self.__projection)))<EOL>
True if results are guaranteed to contain a unique set of property
        values.

        This happens when every property in the group_by is also in the projection.