Swap the Clipboard string(previously copied string) with a Selected string/a Pointed word in code or Swap two selected string/poited word, with multiselection in code.
I had thought about writing a similar one, which would've had a slightly different flow for swapping pieces of text:
point to or select some text
alt + s marks the current text
point to or select some other text
alt + s swaps the first with the second
The advantage of this flow is that you don't need to make multiple selections, which generally involve the mouse in all but trivial cases, and so can select text to swap however you normally would.
Thought this might be a cool extra command for the extension, let me know what you think!