title: Dynamic function docstring
body: <p>I'd like to write a python function that has a dynamically created docstring.  In essence for a function <code>func()</code> I want <code>func.__doc__</code> to be a descriptor that calls a custom <code>__get__</code> function create the docstring on request.  Then <code>help(func)</code> should return the dynamically generated docstring.</p>
  
  <p>The context here is to write a python package wrapping a large number of command line tools in an existing analysis package.  Each tool becomes a similarly named module function (created via function factory and inserted into the module namespace), with the function documentation and interface arguments dynamically generated via the analysis package.</p>