Assigning multiple attribs doesn't work

This is example code I'm trying to use.
```
self._campos.xz = mat2(c, -s, s, c) * self._campos.xz
```

This issue forces to write less intuitive code.
```
xz = mat2(c, -s, s, c) * self._campos.xz
self._campos.x = xz.x
self._campos.z = xz.y
```
