Additional behaviour required of a state declared with use Ussd.State, continue: true.
Passed to Ussd.use_continuing_state/4 under :confirm mode: when a caller
redials into a session that timed out, this state's render/1 asks whether to
resume, and confirm/0 returns the Ussd.Decision that recognizes a "yes".
Summary
Callbacks
@callback confirm() :: Ussd.Decision.t()
The decision that recognizes the caller agreeing to resume their previous session.