def _sink(self, k):
while 2 * k <= self.size:
j = 2 * k
if j < self.size and less(self.heap[j], self.heap[j + 1]):
j += 1
if not less(self.heap[k], self.heap[j]):
break
exch(self.heap, k, j)
k = j
def _swim(self, k):
while k > 1 and less(self.heap[k / 2], self.heap[k]):
exch(self.heap, k / 2, k)
k = k / 2
