Implement add_d_leaves, a function that takes in a Tree instance t and mutates it so that at each depth d in the tree, d leaves with labels v are added to each node at that depth. For example, we want to add 1 leaf with v in it to each node at depth 1, 2 leaves to each node at depth 2, and so on.

Recall that the depth of a node is the number of edges from that node to the root, so the depth of the root is 0. The leaves should be added to the end of the list of branches.

def add_d_leaves(t, v):

"""Add d leaves containing v to each node at every depth d.

>>> t1 = Tree(1, [Tree(3)])

>>> add_d_leaves(t1, 4)

>>> t1

Tree(1, [Tree(3, [Tree(4)])])

>>> t2 = Tree(2, [Tree(5), Tree(6)])

>>> t3 = Tree(3, [t1, Tree(0), t2])

>>> add_d_leaves(t3, 10)

>>> print(t3)

3

1

3

4

10

10

10

10

10

10

0

10

2

5

10

10

6

10

10

10

"""

"*** YOUR CODE HERE ***"