Erk, apologies, this part of the PR is getting noisy ... but I've re-run your doc-string example, which yields a different result ...
```
>>> from iris.util import remap_cube_dimensions as remap
>>> cube = iris.load_cube(iris.sample_data_path('air_temp.pp'))
>>> cube.data 
...
>>> cube.shape
(73, 96)
>>> remap(cube, axes_to_add=[0])
>>> cube.shape
(1, 73, 96)
>>> remap(cube, axes_to_add=[1, 3], axes_to_remove=[0])
>>> cube.shape
(1, 73, 96, 1)
>>> 
```