bin_renamer.py

import os, sys


def renamer (oldname):
	if oldname[-2:] == "py" or oldname[-3] == ".":
		return oldname
	else:
		name = oldname[:-3] + "bin"
		return name



if __name__ == "__main__":

	for filename in os.listdir('.'):
		filename = os.rename(filename, renamer(filename))