def extract(self, output_file):
"""
Restore the compressed data
"""
br = BitReader(self.file)
root = self._read_trie(br)
# number of bytes to write
length = int(br.readbits(8))
bw = BitWriter(output_file)
# decode using the Huffman trie
for i in xrange(length):
node = root
while not node.is_leaf:
bit = br.readbit()
if bit:
node = node.right
else:
node = node.left
# write the character to output
bw.writebits(node.char, 8)
