title: Simple Recursion?
body: <p>I'm new to programming and have had a hard time understanding recursion. There's a problem I've been working on but can't figure out. I really just don't understand how they are solvable.</p>
  
  <p>"Define a procedure plus that takes two non-negative integers and returns their sum. The only procedures (other than recursive calls to plus) that you may use are: zero?, sub1, and add1. </p>
  
  <p>I know that this is a built in functions in scheme, so I know they're possible to solve, I just don't understand how. Recursion is so tricky! </p>
  
  <p>Any help would be greatly appreciated! 
  =] Thanks</p>
  
  <p>I'm working in Petite Chez Scheme (with the SWL editor) </p>