title: Evaluate string as an expression
body: <p>How would you convert a string like "2 + 3 + 4" into an expression that ruby will return the value of 9</p>
  
  <p>but as an integer. I was thinking some sort of .each block, but I feel that would be a very long function. If that is the only way, then fine. Just wanted some other eyes on it. </p>