code: function transformClasses(value) {
          if (t.isStringLiteral(value)) {
              value.value.split(" ").forEach(function(cls) {
                  renderer.addClass(cls);
              });
          } else if (t.isJSXExpressionContainer(value)){
              renderer.handleClasses(value.expression);
          } else {
              error(value, "Unknown class specification type.");
          }
      }
docs: Transforms the class specification into either a sequence of add-class
  renderer calls or a handler function call.