Technically all coordinates in the original cube are "present" in the subcubes...

This is a hard thing to write-up, but I've had a go (it is by no means perfect... modification/alternatives welcome):

```
Return an iterator of all cubes given the non-scalar coordinates desired. 

Returns an iterator of all sub-cubes which result from iterating over all dimensions element-by-element. To maintain certain dimensions from the original cube, coordinates can be specified which will not be iterated over and will remain extensive in the sub-cubes.

```