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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 start_tree(self, tree, filename):
 """Some fixers need to maintain tree-wide state. This method is called once, at the start of tree fix-up. tree - the root node of the tree to be processed. filename - the name of the file the tree came from. """

        self.used_names = tree.used_names
        self.set_filename(filename)
        self.numbers = itertools.count(1)
        self.first_log = True