Dear Julia Community,

I struggle to understand the append!-function and I would much appreciate any help:) Consider the following minimal example

```
x_0 = [1;1]
x_1 = x_0
x_2 = x_0
append!(x_1,x_2)
```

As a result all three vectors have now a length of 4. However, the example

```
x_0 = [1;1]
x_1 = [1;1]
x_2 = x_0
append!(x_1,x_2)
```

creates the expected result: `x_1`

has length 4, while the other two have a length of 2.

Thank you very much for your help!