```\n/\*\*\n \* @dev locked status, only applicable before unlock\_date\n \*/\nbool public \_is\_locked = true;\n\n/\*\*\n \* @dev Modifier that only allows function to run if either token is unlocked or time has expired.\n \* Throws if called while token is locked.\n \*/\nmodifier onlyUnlocked() {\n    require(!\_is\_locked || now > unlock\_date);\n    \_;\n}\n\n/\*\*\n \* @dev Internal function that unlocks token. Can only be ran before expiration (give that it's irrelevant after)\n \*/\nfunction \_unlock() internal {\n    require(now <= unlock\_date);\n    \_is\_locked = false;\n```\n