text: /* */ 
  var falafel = require('../index');
  var src = 'console.log(beep "boop", "BOOP");';
  function isKeyword(id) {
    if (id === 'beep')
      return true;
  }
  var output = falafel(src, {isKeyword: isKeyword}, function(node) {
    if (node.type === 'UnaryExpression' && node.operator === 'beep') {
      node.update('String(' + node.argument.source() + ').toUpperCase()');
    }
  });
  console.log(output);
  