def link(self, other_tree):
        """Make other_tree the son of self. Both trees must have the
        same rank, and other_tree must have a larger minimum priority
        """
        if self.rank != other_tree.rank:
            raise LinkError()
        if self.value > other_tree.value:
            raise LinkError()
        self.children.append(other_tree)
        self.rank += 1 
        return True
Make other_tree the son of self. Both trees must have the
        same rank, and other_tree must have a larger minimum priority
        
recipes/Python/511508_Binomial_Queues/recipe-511508.py