pycycle - Tool for pinpointing circular imports in Python. Find cyclic imports in any project.
pylint - A Python source code analyzer which looks for programming errors, helps enforcing a coding standard and sniffs for some code smells.
prospector - Inspects Python source files and provides information about type and location of classes, methods etc.
mypy - Optional static typing for Python 2 and 3
attrs - Python Classes Without Boilerplate.