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

    arrayExpr = Forward()
    def countFieldParseAction(s, l, t):
        n = int(t[0])
        (arrayExpr << ((n and Group(And(([expr] * n)))) or Group(empty)))
        return []
    return (Word(nums).setName('arrayLen').setParseAction(countFieldParseAction, callDuringTry=True) + arrayExpr)

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

def countedArray(expr):