function isDecCode(c) {
  return ((0x30/* 0 */ <= c) && (c <= 0x39/* 9 */));
}
@param {string} expr
@param {JSONObject} val
@param {string} path
@param {PlainObject|GenericArray} parent
@param {string} parentPropName
@param {JSONPathCallback} callback
@param {boolean} literalPriority
@returns {ReturnObject|ReturnObject[]}