code: function filter_date(value) {
      var m = DATE_RE.exec(value);
      if(m == null) throw OptError('Expected a date representation in the "yyyy-mm-dd" format.');
      return new Date(parseInt(m[0]), parseInt(m[1]), parseInt(m[2]));
  }
docs: Switch argument filter that expects a Date expression. The date string MUST be formated as: "yyyy-mm-dd" An exception is throwed if the criteria is not matched. An DATE object is returned on success.