code: @Override
      public CloseableValue<Boolean> asBoolean() {
          final Class<?> callerClass = ReflectionHelper.getDirectCallerClass();
          return bindSingeValue(Boolean.TYPE, callerClass);
      }
docs: Evaluates the XPath as a boolean value. This method is just a shortcut for as(Boolean.TYPE);
  
  @return true when the selected value equals (ignoring case) 'true'