Use public data field.
Complete numeric type validation.
0.1.5
Assert on WRONGTYPE (string).
Assert on WRONGTYPE (hash).
0.1.6
Auth required: requirepass must be string.
0.1.7
Use quit command definition.
Arity: do not account for range length.

Ping, shutdown etc have arity -1 and 0,0,0 for first, last and step. It
is now the responsibility of the command validation function to further
validate the argument length.
0.1.8