def __construct_trie(self):
queue = PriorityQueue.heapify([Huffman.Node(k, v) for (k, v) in self.frequencies.items()])
self.num_tries_nodes = queue.size()
while queue.size() > 1:
x = queue.del_min()
y = queue.del_min()
parent = Huffman.Node(0, x.freq + y.freq, x, y, )
queue.insert(parent)
self.num_tries_nodes += 1
self.trie = queue.del_min()
