<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def is_topk(self, topk=10, reverse=False):
 """ Create an SArray indicating which elements are in the top k. Entries are '1' if the corresponding element in the current SArray is a part of the top k elements, and '0' if that corresponding element is not. Order is descending by default. Parameters topk : int The number of elements to determine if 'top' reverse : bool If True, return the topk elements in ascending order Returns ------- out : SArray (of type int) Notes ----- This is used internally by SFrame's topk function. """

        with cython_context():
            return SArray(_proxy = self.__proxy__.topk_index(topk, reverse))