Listified Tokens, or Somebody's JavaScript C+ Homework

Convert strings of the form "(1, 2, 3), (4, 5, 6), (7, 8, 9)" into multidimensional arrays of the form [[1, 2, 3], [4, 5, 6], [7,8,9]] in not super-efficient fashion.

See also, https://replit.com/@365Erik/Listified-Tokens-or-Somebodys-JavaScript-Homework.