Maybe I'm too into numpy, but do you think it'd be more clear to document this as `dtype`? The function actually accepts any dtype (i.e. `'int', int, '<i4'`, etc).
As an example, `np.arange` documents a parameter with the same functionality like this:
```
dtype : dtype
    The type of the output array.  If `dtype` is not given, infer the data
    type from the other input arguments.
```