def register_initial(self, circuit: cirq.AbstractCircuit, transformer_name: str) -> None:
        """Register the beginning of a new transformer stage.

        Args:
            circuit: Input circuit to the new transformer stage.
            transformer_name: Name of the new transformer stage.
        """
        if self._stack:
            self._logs[self._stack[-1]].nested_loggers.append(self._curr_id)
        self._logs.append(_LoggerNode(self._curr_id, transformer_name, circuit, circuit))
        self._stack.append(self._curr_id)
        self._curr_id += 1
Register the beginning of a new transformer stage.

        Args:
            circuit: Input circuit to the new transformer stage.
            transformer_name: Name of the new transformer stage.
        
cirq-core/cirq/transformers/transformer_api.py