def __init__(self, valid_commands):
        """
        Initialize a new Invoker instance.

        @param valid_commands: A list of command classes this invoker can handle.
        """
        self._history = []
        self._valid_commands = valid_commands

        Initialize a new Invoker instance.

        @param valid_commands: A list of command classes this invoker can handle.
        
pypattyrn/behavioral/command.py