Using the Action Editor to mirror/Reverse a set of Keys for a WalkCycle?

Hey all, Im using 4.9 (dont ask), and im going through a tutorial on a walk Cycle, the Tut shows the action editor has a button that copies a mirrored set of keys for the opposite leg, if that makes sense, but on my Blender it isnt where it is supposed to be. i have found a menu that says mirror, but i dont know how to work it and all it does is more keys around in a confusing way… Any one know where this button is now?

EDIT: After looking around a bit have seen this button everywhere, its called the ‘Paste Flip Pose’ Button.

Thanks guys

SOLVED: It was in the armature Menu, Piece of cake and works perfectly.