Run with python3 game.py
Given more time, both the player_extra_cards_sequence() and dealer_extra_cards_sequence() functions could be looked at to make these functions easier to test.
In addition to writing additional features for the game as listed in the brief, it would be interesting to add a multiplayer element to the game for more human / CPU players. The aggressiveness of the CPU player to twist could be set by the user via command line args.