code: public function addExtension(
          ExtensionInterface $ext,
          /*# bool */ $forceOverride = false
      ) {
          foreach ($ext->methodsAvailable() as $method) {
              if (isset($this->extension_methods[$method]) &&
                  !$forceOverride) {
                  throw new LogicException(
                      Message::get(Message::MSG_EXTENSION_METHOD, $method),
                      Message::MSG_EXTENSION_METHOD
                  );
              }
              $this->extension_methods[$method] = $ext;
          }
          $ext->boot($this);
          return $this;
      }
docs: {@inheritDoc}