Write a static method, copy, that, given a binary tree, returns a copy of the tree. Because not every object implements the copy method, you should not copy objects to which the tree refers. This is...

Write a static method, copy, that, given a binary tree, returns a copy of the tree. Because not every object implements the copy method, you should not copy objects to which the tree refers. This is referred to as a shallow copy.

Design an interface for general trees—trees with unbounded degree. Make this interface as consistent as possible with Binary Trees when the degree of a tree is no greater than 2.