def _effective_signals_schema(self) -> "SignalSchema":
        """Effective schema used for user-facing API like collect, to_pandas, etc."""
        signals_schema = self.signals_schema
        if not self._sys:
            return signals_schema.clone_without_sys_signals()
        return signals_schema
Effective schema used for user-facing API like collect, to_pandas, etc.
src/datachain/lib/dc/datachain.py