docs: def click_on_label(self, label):
      """
      Click on the given label.
  
      On a correctly set up form this will highlight the appropriate field.
      """
  
      elem = ElementSelector(
          world.browser,
          str('//label[normalize-space(text())=%s]' % string_literal(label)),
          filter_displayed=True,
      )
      if not elem:
          raise AssertionError(
              "Cannot find a label with text '{}'.".format(label))
      elem.click()