I started using this recently. If you do a lot of Python, you'll sometimes find yourself desperate for breadcrumbs, little print statements scattered throughout your code as you try to figure what you told it to do, since it's obviously not doing what you want it to do. I'd used inspect previously to unravel exception handlers; there's a customized one inside the Isilon UI, so if the product fails in the field the exception will be logged to a file for later analysis, but this is a nice little routine. It's basically a pythonic version of the C LINE macro. Wherever you think you might need a debugging statement, put if DEBUG: print _line(), foo, bar, baz and you'll not only get the fields you want to see, but also the name of the function/method, and the line number of the print statement.

import inspect
def _line():
    info = inspect.getframeinfo(inspect.currentframe().f_back)[0:3]
    return '[%s:%d]' % (info[2], info[1])

Use as needed.