import sys

def max_check(arr):       # My version, always returns None
	print(arr) 
	if len(arr) == 1:
		print(arr)        # It looks like the largest number is here!
		return arr[0]     # But now it's gone!
	elif arr[0] < arr[1]: # Not very tidy, but is this approach a problem?
		arr.pop(0)
		max_check(arr)
	elif arr[0] >= arr[1]:
		arr.pop(1)
		max_check(arr)


def maximum(lst):         # Author's version, returns correct number
    print(lst)
    if len(lst) == 1:
        print(lst)        # Why doesn't this print the largest number to console?
        return lst[0]
    else:
        m = maximum(lst[1:])
        if m > lst[0]:
            return m
        else:
            return lst[0]
	

def main():
	print(max_check([1, 2, 3, 2]))
	print(maximum([1, 2, 3, 2]))
	
if __name__ == "__main__":
    main()

Output:
[1, 2, 3, 2]
[2, 3, 2]
[3, 2]
[3]
[3]     # Mission accomplished?
None    # Nope.  

[1, 2, 3, 2]
[2, 3, 2]
[3, 2]
[2]
[2]     # huh?
3       # huh??