$ click_

  Click is a Python package for creating beautiful command line interfaces
  in a composable way with as little amount of code as necessary.  It's the
  "Command Line Interface Creation Kit".  It's highly configurable but comes
  with good defaults out of the box.

  It aims to make writing command line tools quick and fun without causing
  user frustration from the inability to implement a desired CLI API.

  Click in three points:

  -   arbitrary nesting of commands
  -   automatic help page generation
  -   supports lazy loading of subcommands at runtime

  Read the docs at http://click.pocoo.org/

  This library is work in progress.  Please give feedback!