safe wrapper
Also written: safe wrappers
A normal function that checks the rule an unsafe operation needs, then does it, so callers can't misuse it. `last_price` checks for an empty list before calling `price_at`.
Also written: safe wrappers
A normal function that checks the rule an unsafe operation needs, then does it, so callers can't misuse it. `last_price` checks for an empty list before calling `price_at`.