code: function (cssClasspath) {
              var prefixClass = this.__prefixes[cssClasspath];
              if (!prefixClass) {
                  prefixClass = this.__PREFIX + this.__NEXT_PREFIX_INDEX;
                  this.__NEXT_PREFIX_INDEX += 1;
  
                  this.__prefixes[cssClasspath] = prefixClass;
              }
  
              return prefixClass;
          }
docs: Get the prefix for a CSS template.
  @param {String} cssClasspath CSS template classpath
  @return {String) class used as a prefix
  @private