Contains constructor

Implementation

Contains()
  : super(
      methodName: "contains",
      arity: 1,
      targetType: NativeMethodTarget.string,
      function: (target, _, args) {
        final arg = args[0];
        if (arg is! String) {
          throw RuntimeError("contains() takes a string as an argument.");
        }
        return target.contains(arg);
      },
    );