Problem 3.3: Iterator Tree Link Tree Iterator (100 pts)

Implement the function funcs, which is a generator that takes in a linked list link and yields functions.

The linked list link defines a path from the root of the tree to one of its nodes, with each element of link specifying which branch to take by index. Applying all functions sequentially to a Tree instance will evaluate to the label of the node at the end of the specified path.

For example, using the Tree t defined in the code, funcs(Link(2)) yields 2 functions. The first gets the third branch from t -- the branch at index 2 -- and the second function gets the label of this branch.

>>> func_generator = funcs(Link(2)) # get label of third branch
>>> f1 = next(func_generator)
>>> f2 = next(func_generator)
>>> f2(f1(t))
4

def funcs(link):
    """
    >>> t = Tree(1, [Tree(2,
    ...                   [Tree(5),
    ...                    Tree(6, [Tree(8)])]),
    ...               Tree(3),
    ...               Tree(4, [Tree(7)])])
    >>> print(t)
    1
      2
        5
        6
          8
      3
      4
        7
    >>> func_generator = funcs(Link.empty) # get root label
    >>> f1 = next(func_generator) 
    >>> f1(t)
    1
    >>> func_generator = funcs(Link(2)) # get label of third branch
    >>> f1 = next(func_generator)
    >>> f2 = next(func_generator)
    >>> f2(f1(t))
    4
    >>> # This just puts the 4 values from the iterable into f1, f2, f3, f4
    >>> f1, f2, f3, f4 = funcs(Link(0, Link(1, Link(0))))
    >>> f4(f3(f2(f1(t))))
    8
    >>> f4(f2(f1(t)))
    6
    """
    "*** YOUR CODE HERE ***"