An enjoyably curious sequence yesterday...
Opener started with One Spade, Two Diamonds response.
Opener repeated spades; Responder showed clubs.
Opener repeated spades yet again (never jumping), to Responder.
The curious solution was the cue of Four Hearts. Four Hearts operated as a trump cue, contextually, at least in a sense. This was just what Opener needed to hear (and thus the good decisions to not blast Four Spades at any point), and the slam was reached.
Not that tricky, except for the rest of the field.