The Mustache engine for Pattern Lab / Node
If it's missing from your project for any reason,
npm install patternengine-node-mustache should do the trick.
Extensions to default Mustache functionality
Pattern Parameters and Style Modifiers are convenient syntax extensions to Mustache that allow you change the behavior of a pattern you're calling from within another. They're not necessary in other template engines because the others have natively supported ways of passing arguments to template partials.