title: How to do this in Groovy?
body: <p>Lets say that there are two variable, the value of the variable is taken from the users. That is:</p>
  
  <pre><code>a=0
  b=1
  c=a-b
  </code></pre>
  
  <p>For some cases i need the variable <code>c</code> to be always positive, is there is any method in Groovy to do this?</p>