code: function (self, args) {
      var pathname = isRelative(args[0]) ? args[0] : ('./' + args[0]);
  
      self.context.requireAsset(pathname);
    }
docs: The `require` directive functions similar to Ruby's `require`. It provides a way to declare a dependency on a file in your path and ensures it's only loaded once before the source file.  `require` works with files in the environment path:  //= require "foo.js"  Extensions are optional. If your source file is ".js", it assumes you are requiring another ".js".  //= require "foo"  Relative paths work too. Use a leading `./` to denote a relative path:  //= require "./bar"