recursion.py

def recursion1(number):
    evens = []
    
    if number % 2 == 0:
        evens += [number]
    if number <= 0:
        return evens

    evens += recursion1(number - 1)
    return evens

print(recursion1(10))

def recursion2(number):
    if number > 10:
        return number
    return number + recursion2(number + 1)

print(recursion2(3))

#        +-----------+
#        |           |
#     +-----+     +-----+
#     |     |     9     2
#   +---+ +---+ 
#   3   4 8   5

tree = [[[3,4], [8,5]], [9, 2]]

def recursion3(node):
    if type(node) == int:
        return node

    left = recursion3(node[0])
    right = recursion3(node[1])
    return max(left, right)

print(recursion3(tree))