Flip 3d view horizontally.

This one is for grease pencil artists. Every drawing program has the feature to flip the drawing horizontally. This helps in revealing errors like balance and skewing. In blender the only way to do this is to look from the other side or if in camera view, by scaling the camera by -1 due X-axis. It would be good to have a single key that flips the view no matter where I am looking from.

Thankyou.