def childDataReceived(childFD, data):
        """
        Called when data arrives from the child process.

        @type childFD: L{int}
        @param childFD: The file descriptor from which the data was
            received.

        @type data: L{bytes}
        @param data: The data read from the child's file descriptor.
        """

        Called when data arrives from the child process.

        @type childFD: L{int}
        @param childFD: The file descriptor from which the data was
            received.

        @type data: L{bytes}
        @param data: The data read from the child's file descriptor.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/interfaces.py