title: Mutually recursive functions - exercise not making sense to me
body: <p>I know this is a silly way to determine even-odd numbers. It is just a lesson in recursion, and probably some other concepts as well. </p>
  
  <p>The problem.</p>
  
  <p>When I follow the logic, it looks like it doesn't matter what value you give "n", it will always eventually equal "0" and always end up "false".</p>
  
  <p>What is going on?</p>
  
  <pre><code>function isOdd(x) {
      return !isEven(x);    
  }
  
  function isEven(x) {
      if(x===0) {
          return true;
      } else {
          return isOdd(x-1);
      }
  }
  </code></pre>