src/vs/platform/contextkey/common/contextkey.ts/ContextKeyNotExpr/create
class ContextKeyNotExpr:	public static create(key: string, negated: ContextKeyExpression | null = null): ContextKeyExpression {
		const constantValue = CONSTANT_VALUES.get(key);
		if (typeof constantValue === 'boolean') {
			return (constantValue ? ContextKeyFalseExpr.INSTANCE : ContextKeyTrueExpr.INSTANCE);
		}
		return new ContextKeyNotExpr(key, negated);
	}