title: Multiplication using only recursion
body: <p>Hey I'm trying to write some code that doesn't use any of the normal python code for multiplication, division or loops.  Right now im trying to do the multiplication part.  Here's what i have so far.</p>
  
  <pre><code>def incr(a):
  '''Returns the next integer after a'''
  return a + 1
  
  def zero(a):
  '''Returns True if a is zero'''
  return a == 0
  
  def decr(a):
  '''Returns the integer before a'''
  return a -1
  
  def add(a, b):
      '''Returns the sum of a and b'''
      # using only incr, decr, zero, and recursion
  
      a = incr(a)
  
      b = decr(b)
  
      if zero(b) != 1:
          add(a,b)
  
      if zero(b) != 0:
          print(a)
  
      #return 0
      return a #edit
  
  def mult(a, b):
       '''Returns the product of a and b'''
       # using only add, incr, decr, zero, and recursion
  
      add(a,a)
  
      b= decr(b)
  
      if zero(b) != 0:
          mult(a,b)
  
      if zero(b) != 0:
          print(a)
  
      #return 0
      return a #edit
  
   mult(2,4)
  </code></pre>
  
  <p>However, the code for the <code>mult()</code> is only adding, not multiplying.  for this I should be getting <code>8</code>,but I'm only getting <code>4</code>. So for some reason it's not running the script again.</p>