My customization to make it easy to learn python3 using emacs without breaking working of existing python related stuff

python3.el

;; Python3 customization

;; Path to Python3 only required for windows.. :)
(setq python3-executable "C:/Users/invakam2/Documents/Programs/python3.2/App/python.exe")

;; Function similar to python-shell but this
;; is my crude implementation

(defun python3-shell()
  (interactive)
  
  ;; explicit-shell-file-name if non nil it will be used by M-x shell
  ;; as shell to be executed
  (setq explicit-shell-file-name
        python3-executable)

  ;; Now launch shell (Python3)
  (shell)

  ;; Lets have Python3 as name
  (rename-buffer "*Python3*")

  ;; Now reset the variable I don't want to mess around
  (setq explicit-shell-file-name nil))

(defun run-python3(script-file)
  ;; Gee I don't know how this works nor I know this is how we take input
  ;; D goes for Directory and I threw a stone in dark thinking f takes file
  ;; and it did take file name!..
  ;; Now don't ask me how the file-name gets assigned to script-file symbol
  ;; I don't have a clue!
  
  (interactive "fScript Name: ")
  (let (
        ;; Output buffer
        ( python-output "Python3-Output"))
    ;; Split winows vertically
    (split-window-vertically)
    ;; move to down part of split windows
    (windmove-down)

    ;; now create and change to buffer 
    (switch-to-buffer (get-buffer-create python-output))

    ;; Insert the output to buffer!
    (insert  (apply #'call-process python3-executable nil t nil (list script-file)))))

Holy cow this is useful! I am new to Emacs and have been groaning over my inability to run both python 2 and python 3 shells. Nothing I did to the python mode files helped. Now there's this!