Implementation of the Stack data structure using GenServer

The file .tool-versions for asdf contains the Elixir version to use: 1.11.1.

Through the Stack module to call the API methods that encapsulate the OTP/GenServer calls:

iex(1)> {:ok, stack} = Stack.start_link([])
{:ok, #PID<0.180.0>}
iex(2)> Stack.push(stack, 3)
:ok
iex(3)> Stack.push(stack, 6)
:ok
iex(4)> Stack.push(stack, 1)
:ok
iex(5)> Stack.pop(stack)
1
iex(6)> Stack.state(stack)
[6, 3]

Run mix test :

➜  stack (master) ✗ mix test
.........

Finished in 0.04 seconds
9 tests, 0 failures

Randomized with seed 404803