The following code results in test_var1 having "5" appended into it, despite that never being done.
```
test_var1 = [1,2,3,4];
test_var2 = [];
test_var3 = [5];
test_var2 = test_var1;
test_var2 pushBack (test_var3 select 0);
hint str test_var1; //Should return [1,2,3,4], instead returns [1,2,3,4,5]
```
This method, however, appears to work properly.
```
test_var1 = [1,2,3,4];
test_var2 = [];
test_var3 = [5];
{test_var2 pushBack _x} forEach test_var1;
test_var2 pushBack (test_var3 select 0);
hint str test_var1; Properly returns [1,2,3,4]
```