Pyty is a static typechecker for Python source code. Like pylint and PyChecker, Pyty is a tool run on source code to catch the compile-time errors of less-dynamic languages. Pyty is meant to be used in instances when the security of ensuring valid logic is more important than the flexibility of Python's dynamic-typing fetaures.
Pyty is currently at a very rudimentary stage, and is being developed by Jeff Ruberg as a senior thesis project at Wesleyan University.