code: def topKFrequent(self, words, k):
      count = collections.Counter(words)
      # Note that python heapq only support min heap
      # So, we can make the value negative to create a max heap
      heap = [(-freq, word) for word, freq in count.items()]
      heapq.heapify(heap)
      return [heapq.heappop(heap)[1] for _ in xrange(k)]
  
label_desc: Use image node_id 1 for calling the Solution obj's underlying member method code with example usage: obj.topKFrequent(words, k) and returns: unknown