docs: public Number getNumber(String key) throws JSONException {
          Object object = this.get(key);
          try {
              if (object instanceof Number) {
                  return (Number)object;
              }
              return stringToNumber(object.toString());
          } catch (Exception e) {
              throw new JSONException("JSONObject[" + quote(key)
                      + "] is not a number.", e);
          }
      }