update all necessary packages pip code example

Example 1: python update installed packages

py2
$ pip install pip-review

$ pip-review --local --interactive

py3
$ pip3 install pip-review

$ py -3 -m pip_review --local --interactive

Example 2: update all modules python in cmd

import pkg_resources
from subprocess import call

packages = [dist.project_name for dist in pkg_resources.working_set]
call("pip install --upgrade " + ' '.join(packages), shell=True)