title: Calling functions from a spreadsheet formula
body: <p>I'm starting to learn Google Apps Script and trying to complete "Your First Custom Function" tutorial. Maybe something has changed and they forgot to update the tutorial? When I type <code>=in2mm(10)</code> in a cell, it shows <code>#NAME</code> and <code>Unknown function name</code> popup is displayed.</p>
  
  <p>So how do I call my own functions from a spreadsheet formula?</p>