Why are you testing the boolean value of coord (I suspect this is pre-existing code)? I believe plot_defn.coords will be either be ```[coord]``` or ```[None]``` (I'm not certain though - sorry if I'm talking nonsense). If it is, this code can become:
```python
u_object = None
if isinstance(v_object, iris.cube.Cube):
    plot_defn = _get_plot_defn(v_object, iris.coords.POINT_MODE, ndims=1)
    u_object, = plot_defn.coords
return u_object
```
or am I missing something?