code: def _call_pip(*args):
      
      all_args = [sys.executable, "-m", "pip"] + list(args)
      print("> {}".format(" ".join(all_args)))
      subprocess.check_call(all_args)
docs: Invoke pip *safely* and in the *supported* way:
      https://pip.pypa.io/en/latest/user_guide/#using-pip-from-your-program