human
I wrote the below code

    path = path2fsn(path)
    def repl_func(match):
        return environ.get(match.group(1), match.group(0))
    path = re.compile('\\$(\\w+)', flags=re.UNICODE).sub(repl_func, path)
    if (os.name == 'nt'):
        path = re.sub('%([^%]+)%', repl_func, path)
    return re.sub('\\$\\{([^\\}]+)\\}', repl_func, path)

What's a good function header?

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

def expandvars(path):