Check if set contains a value

main.dart

void main() {
  var x = new Set<String>();
  x.add("foo");

  {
    var e = "foo";
    var b = x.contains(e);
    print('x contains ${e}: ${b}');
  }
  {
    var e = "barbaz";
    var b = x.contains(e);
    print('x contains ${e}: ${b}');
  }
}