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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 set_ownership(self):
 """Recursivelt set the parent, section and doc for a children"""

        assert self.section is not None

        for t in self.children:
            t.parent = self
            t._section = self.section
            t.doc = self.doc
            t.set_ownership()