Fixes a bug where 0-tuples’ description did not include the opening parenthesis.
Tuples define a debug description.
Tuples can be hashed.

Hashing is done by dividing the hash's bits into n equal-sized partitions (one per element), modulus/shifting the elements’ hashes into those partitions, and adding the tuple’s count. I’m not certain of the quality of this approach, but it is at least a start.