Given a loop over batches of an iterable and an operation that should
        be performed every few elements. Determine whether the operation should
        be called for the current index.

def _every(times, step_size, index):
        """
        Given a loop over batches of an iterable and an operation that should
        be performed every few elements. Determine whether the operation should
        be called for the current index.
        """
        current = index * step_size
        step = current // times * times
        reached = current >= step
        overshot = current >= step + step_size
        return current and reached and not overshot