saved normally.
*  A string of the form `dim0 dim1 ... dimN-1 slice-spec` where the
   `dimI` are the dimensions of the larger tensor and `slice-spec`
   specifies what part is covered by the tensor to save.

`slice-spec` itself is a `:`-separated list: `slice0:slice1:...:sliceN-1`
where each `sliceI` is either:

*  The string `-` meaning that the slice covers all indices of this dimension