code: public boolean pages_isFan(Long pageId)
      throws FacebookException, IOException {
      return extractBoolean(this.callMethod(FacebookMethod.PAGES_IS_FAN,
                                            new Pair<String,CharSequence>("page_id", pageId.toString())));
    }
docs: Checks whether the logged-in user is a fan of the page with the given <code>pageId</code>.
  @param pageId the ID of the page
  @return true if the logged-in user is a fan of the page
  @see <a href="http://wiki.developers.facebook.com/index.php/Pages.isFan">
  Developers Wiki: Pages.isFan</a>