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

    def step(ctxt, key, val):
        ctxt.append((u'%s:%s' % (key, val)))
    def finalize(ctxt):
        return u','.join(ctxt)
    return ([], step, finalize)

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

def IdentifiersConcat():