How To Make This Recursive Function Iterative In Python?

Usually I'm good with this type of thing, but this is bugging me. I had to write this function last week, and writing it recursively made the most sense, although now I'm trying to

Solution 1:

def ClosestCommonAncestor(otu1, otu2, tree):
    while tree[otu1][0][0] != tree[otu2][0][0]:
        otu1,otu2,tree = tree[otu1][0],tree[otu2][0],tree
    return tree[otu1][0]

Do note that it should be possible to add functionality to the recursive version. I would also suggest defining a Tree(*children) class to make things clearer.

Solution 2:

def ClosestCommonAncestor (otu1,otu2,tree):
    while True:
        a = tree[otu1][0]
        b = tree[otu2][0]
        if a[0] == b[0]:
            return a
        otu1 = a
        otu2 = b