aenhsaihan

def build_root(self, iterable):
    collection = list(iterable)
    assert(len(collection) != 0)
    if len(collection) % 2 != 0:
        collection.append(collection[-1])
    collection = [self.__Node(self.digest(x)) for x in collection]
    return self.__build_root(collection)

def __build_root(self, collection):
    size = len(collection)