UNSUBSCRIBE
Unsubscribes the connection from a topic
Input stack: subscription
Output stack: ``
UNSUBSCRIBE
stops connected client to from receiving messages from a
topic it previously subscribed to.
PumpkinDB> "topic" SUBSCRIBE UNSUBSCRIBE
Allocation
Runtime allocations necessary for the server
Errors
EmptyStack error if there is less than one item on the stack
Tests
empty_stack : [UNSUBSCRIBE] TRY UNWRAP 0x04 EQUAL?.