code: def query(self, selector, context=None):
          
          element = self.client.create_element(
              'browser.query', (selector, context))
          return DOMNode.factory(element, self)
docs: Evaluate a CSS selector against the document (or an optional context
          :class:`zombie.dom.DOMNode`) and return a single
          :class:`zombie.dom.DOMNode` object.
  
          :param selector: a string CSS selector
                          (http://zombie.labnotes.org/selectors)
          :param context: an (optional) instance of :class:`zombie.dom.DOMNode`