code: def get_property_value(self, selector, property, by=By.CSS_SELECTOR,
                             timeout=settings.SMALL_TIMEOUT):
          
          if self.timeout_multiplier and timeout == settings.SMALL_TIMEOUT:
              timeout = self.__get_new_timeout(timeout)
          if page_utils.is_xpath_selector(selector):
              by = By.XPATH
          if page_utils.is_link_text_selector(selector):
              selector = page_utils.get_link_text_from_selector(selector)
              by = By.LINK_TEXT
          self.wait_for_ready_state_complete()
          page_actions.wait_for_element_present(
              self.driver, selector, by, timeout)
          try:
              selector = self.convert_to_css_selector(selector, by=by)
          except Exception:
              # Don't run action if can't convert to CSS_Selector for JavaScript
              raise Exception(
                  "Exception: Could not convert {%s}(by=%s) to CSS_SELECTOR!" % (
                      selector, by))
          selector = re.escape(selector)
          selector = self.__escape_quotes_if_needed(selector)
          script = ("""var $elm = document.querySelector('%s');
                    $val = window.getComputedStyle($elm).getPropertyValue('%s');
                    return $val;"""
                    % (selector, property))
          value = self.execute_script(script)
          if value is not None:
              return value
          else:
              return ""
docs: Returns the property value of a page element's computed style.
              Example:
                  opacity = self.get_property_value("html body a", "opacity")
                  self.assertTrue(float(opacity) > 0, "Element not visible!")