Recursion function in Python

Question

Consider this basic recursion in Python:

def fibonacci(number):
    if number == 0: return 0
    elif number == 1:
        return 1
    else:
        return          


        

Answer 1

You can figure this out yourself, by putting a print function in the function, and adding a depth so we can print it out prettier:

def fibonacci(number, depth = 0):
    print " " * depth, number
    if number == 0:
        return 0
    elif number == 1:
        return 1
    else:
        return fibonacci(number-1, depth + 1) + fibonacci(number-2, depth + 1)

Calling fibonacci(5) gives us:

5
 4
  3
   2
    1
    0
   1
  2
   1
   0
 3
  2
   1
   0
  1

We can see that 5 calls 4, which goes to completion, and then it calls 3, which then goes to completion.