code: function findHoistableFunctionDeclarations (ast) {
    var tagged = [];
    traverse.traverse(ast, {
      enter: function (node, parent) {
        if (node.type === 'FunctionDeclaration' && ~node.id.name.indexOf('$')) {
          tagged.push([node, parent]);
        }
      }
    });
  
    return tagged;
  }
docs: Find function declarations which can be hoisted,