def __init__(self, proto, executable, errFlag):
        """
        @param proto: An L{IProtocol} provider.
        @param errFlag: A constant belonging to L{StandardErrorBehavior}
            that determines if stderr is logged or dropped.
        @param executable: The file name (full path) to spawn.
        """
        self.protocol = proto
        self.errFlag = errFlag
        self.executable = executable

        @param proto: An L{IProtocol} provider.
        @param errFlag: A constant belonging to L{StandardErrorBehavior}
            that determines if stderr is logged or dropped.
        @param executable: The file name (full path) to spawn.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/endpoints.py