create module for the loaded shader
function createModule(body, options) {
      body = middleware.sanitize(body)
      if (String(options.parameterize) !== 'false') {
          body = middleware.parameterise(body)
      }
      if (options.module === "es6" || options.module === "es2015") {
          var module = 'export default ' + body + ';\n';
      }
      else {
          var module = 'module.exports = ' + body + ';\n';
      }
      return module
    }