Yes, pyp is interesting. So are some other roughly similar Python tools for doing pipe-like stuff. I had blogged about some of them here, a while ago, including pyp, osh, and pipe (not the Unix pipe system call, but a Python module):

Some ways of doing UNIX-style pipes in Python:

http://jugad2.blogspot.in/2011/09/some-ways-of-doing-unix-st...

And that later inspired me to create an experimental tool called pipe_controller:

Swapping pipe components at runtime with pipe_controller:

http://jugad2.blogspot.in/2012/10/swapping-pipe-components-a...

The above post links (recursively) to a few others, also by me, describing a couple of other ways of using pipe_controller, including this one:

Using PipeController to run a pipe incrementally:

http://jugad2.blogspot.in/2012/09/using-pipecontroller-to-ru...

and also includes the link for it on my Bitbucket account.

There's also plumbum, another such Python module.

I found it cumbersome to do branching in most of the existing python stream tools. I made an alternative, that allows you to use curly brackets for indentation:

https://github.com/ircflagship2/pype

This inspired me to build a similar tool which runs javascript instead.

https://github.com/aynik/sx