Open a buffer with a specific git revision by entering C-x v ~
and typing the name of the branch (e.g. upstream/master).
If you do a task in emacs repeatedly, e.g. type the same set of module imports in python scripts, you can compress that task into a keyboard macro.
M-x start-kbd-macro to start macro recordingM-x kmacro-end-or-call-macro to end macroM-x kmacro-name-last-macro to name macroM-x insert-kbd-macro to save macro