name-boolean-flags-affirmatively

# Boolean names A negated name forces the reader to undo the negation at every use. - Prefer `enabled` to `disabled`, `found` to `not_found`, `valid` to `invalid`. - A parameter that switches behaviour off should still be named for what it controls, with `False` as its value, rather than named for the absence. - Predicates that answer a question read best as `is_`, `has_` or `can_` followed by the thing being asked about. The gain is at the call site: `if enabled:` needs no second thought, and `if not disabled:` never quite does.