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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def encode(self, file, n=DEFAULT_CHALLENGE_COUNT, seed=None, chunksz=None, filesz=None):
 """This function generates a merkle tree with the leaves as seed file hashes, the seed for each leaf being a deterministic seed generated from a key. :param file: a file like object that supports the `read()`, `seek()` and `tell()` methods :param n: the number of challenges to generate :param seed: the root seed for this batch of challenges. by default generates a random seed :param chunksz: the chunk size for breaking up the file: the amount of the file that will be checked by each challenge. defaults to the chunk size defined by check_fraction :param filesz: optional size of the file. if not specified, file size will be detected by seeking to the end of the file and reading the position """

        if (seed is None):
            seed = os.urandom(DEFAULT_KEY_SIZE)
        if (filesz is None):
            file.seek(0, 2)
            filesz = file.tell()
        if (chunksz is None):
            if (self.check_fraction is not None):
                chunksz = int(self.check_fraction * filesz)
            else:
                chunksz = DEFAULT_CHUNK_SIZE
        mt = MerkleTree()
        state = State(0, seed, n)
        seed = MerkleHelper.get_next_seed(self.key, state.seed)
        for i in range(0, n):
            leaf = MerkleHelper.get_chunk_hash(file, seed, filesz, chunksz)
            mt.add_leaf(leaf)
            seed = MerkleHelper.get_next_seed(self.key, seed)
        mt.build()
        state.root = mt.get_root()
        mt.strip_leaves()
        tag = Tag(mt, chunksz, filesz)
        state.sign(self.key)
        return (tag, state)