human
Here's a good function header given the following:
I wrote the below code

    def _is_dir_ignored(root, d):
        if d.startswith(u'.'):
            return True
        return (os.path.join(rel_root, d) in IGNORED_DIRS)
    for (abs_root, dirnames, filenames) in os.walk(PROJECT_ROOT):
        rel_root = os.path.relpath(abs_root, PROJECT_ROOT)
        if (rel_root == u'.'):
            rel_root = u''
        dirnames[:] = [d for d in dirnames if (not _is_dir_ignored(rel_root, d))]
        for filename in filenames:
            if (not filename.endswith(u'.py')):
                continue
            abs_name = os.path.join(abs_root, filename)
            rel_name = os.path.join(rel_root, filename)
            (yield (abs_name, rel_name))

What's a good function header?
assistant
#Here's a good function header.

def walk_python_files():