var a = "Test";
var my_list = [1, a, 2];
print(my_list); # expect: [1, Test, 2]
a = 5;
print(my_list); # expect: [1, Test, 2]
class Foo {
    __init__() {
        this.x = 1;
    }
}

a = Foo();
my_list[1] = a;
print(my_list); # expect: [1, <Foo instance>, 2]
print(a.x); # expect: 1
my_list[1].x = 2;
print(a.x); # expect: 2