Challenge 2: Set, Check, and Remove a Key — Possible Solution
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127.0.0.1:6379> SET session:42 "active"
OK
127.0.0.1:6379> EXISTS session:42
(integer) 1
127.0.0.1:6379> TYPE session:42
string
127.0.0.1:6379> DEL session:42
(integer) 1

WHY THIS WORKS AS AN ANSWER
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Each command maps directly to one step in the task, in the same order
requested:

SET session:42 "active" creates the key with the given value,
returning OK to confirm the write succeeded.

EXISTS session:42 confirms the key is actually present, returning the
integer 1 (Redis's way of representing "true" for a count/existence
check) rather than 0.

TYPE session:42 reports which data structure the key holds — string,
in this case, since it was created with a plain SET.

DEL session:42 removes the key, and its return value (1) tells you
exactly how many keys were actually deleted — useful confirmation that
the deletion targeted a real, existing key rather than silently doing
nothing.