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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 get_obs_leaves(self):
 """Returns the last obs nodes that are leaves """

        obs_leaves = []
        for n in self:
            if n.is_leaf:
                if isinstance(n, ModelNode):
                    l = n.parent
                else:
                    l = n
            if l not in obs_leaves:
                obs_leaves.append(l)
        return obs_leaves