Emacs Lisp to run the current region through Python, then replace the region with the output of the script.

replace-python-region.el

(defun replace-python-exp ()
  "Run the region as a Python script, kill the region, insert the output of the Python script."
  (interactive)
  (let* ((tmp-file (make-temp-file "tmppl"))
         (rb (region-beginning))
         (re (region-end))
         (str (buffer-substring-no-properties rb re)))
    (if (string-match "print" str)
        (progn
          (write-region rb re tmp-file nil 1)
          (kill-region rb re))
      (progn
        (goto-char rb)
        (insert "print(")
        (goto-char (+ 6 re))

        (insert ")")
        (setq re (point))
        (write-region rb re tmp-file nil 1)
        (kill-region rb re)
        (message str)))
    (insert (shell-command-to-string (concat "py " tmp-file)))
    (delete-file tmp-file)))