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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 scale_edges(self, multiplier):
        '''Multiply all edges in this ``Tree`` by ``multiplier``'''
        if not isinstance(multiplier,int) and not isinstance(multiplier,float):
            raise TypeError("multiplier must be an int or float")
        for node in self.traverse_preorder():
            if node.edge_length is not None:
                node.edge_length *= multiplier