In the present case, `precision_` is always a numpy.ndarray. While "array-like" is valid here, it is less precise.

I my opinion (but this may not be the general one) "array-like" is almost never justified when talking about an output argument, because there is very little variability in their types. Telling users that the output is "array-like" means that they are forced to call `np.asarray` before using any numpy method, which is an overhead and causes extra clutter that can be avoided.