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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 fix_identities(self, uniq=None):
 """Make pattern-tree tips point to same object if they are equal."""

        if not hasattr(self, 'children'):
            return self
        uniq = list(set(self.flat())) if uniq is None else uniq
        for i, child in enumerate(self.children):
            if not hasattr(child, 'children'):
                assert child in uniq
                self.children[i] = uniq[uniq.index(child)]
            else:
                child.fix_identities(uniq)