Visual Studio Solution Explorer Collapse All

When dealing with complex visual studio solutions with many projects, the solution explorer can become a mess of opened folders and files.  Solution Explorer remembers which folders you have opened, so if you're like me, you never go back and close the folders once you're done.  You just want to collapse the entire tree structure occasionally.  By default, you can collapse the current node of a tree by pressing the - sign on the number keypad.  But this only collapses the current node, and does not recursively close every sub folder.

This command does exist in Visual Studio, but it is not in the menu at least in the 2015 version that I have.  To use it, you have to assign a keyboard shortcut to it by going to the Tools menu and selecting Options, and then Keyboard like so:

Here I've set up a shortcut, so if I hold down CTRL while pressing CO, it will recursively collapse the current node in Solution Explorer.

UPDATE:  Don't use CTRL C as a starting sequence for your chord.  This will mess up the old standard CTRL C for Copy.  I ended up using CTRL O.