"People say: 'Did you get the idea of Tulip and Pin from...' and then fill in the names of any of half-a-dozen fictional criminal duos. And the answer is no, but I probably got them from the same equation. It's a Law of Narrative that if your gang consists of two people (a gangette) one will be the brains of the outfit and one will supply the muscle and speak like dat. They must both, of course, wear black suits. If there are three of them, that still applies but the new guy will be called Fingers."