title: How to organize helper functions
body: <p>I need to create lot of helper routines for converting strings. </p>
  
  <p>Something like :</p>
  
  <pre><code>String Function1(String s) {}
  </code></pre>
  
  <p>I would like to call them from any <code>Activity</code>.</p>
  
  <p>What is the best way to do this ? Do I need to create a class or not ? I was thinking just to have one separate file with all these functions. Is this a candidate for a package or not ?</p>