human
I wrote the below code

    period = int(max(1, period))
    def _callback(iter_no, sym, arg, aux):
        'The    checkpoint    function.'
        if (((iter_no + 1) % period) == 0):
            save_checkpoint(prefix, (iter_no + 1), sym, arg, aux)
    return _callback

What's a good function header?

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

def do_checkpoint(prefix, period=1):