code: public SeleniumAssert contains(CharSequence... values) {
          if (actual instanceof WebDriver) {
              Strings.instance().assertContains(info,
                      ((WebDriver) actual).getPageSource(), values);
          } else if (actual instanceof WebElement) {
              Strings.instance().assertContains(info,
                      ((WebElement) actual).getText(), values);
          }
          return this;
      }
docs: Checks if a webDriver or WebElement has values.
  
  @param values char sequence compared
  @return SeleniumAssert