docs: public Number optNumber(int index, Number defaultValue) {
          Object val = this.opt(index);
          if (JSONObject.NULL.equals(val)) {
              return defaultValue;
          }
          if (val instanceof Number){
              return (Number) val;
          }
          
          if (val instanceof String) {
              try {
                  return JSONObject.stringToNumber((String) val);
              } catch (Exception e) {
                  return defaultValue;
              }
          }
          return defaultValue;
      }