[Feature Request] `+` to match "at least one"/"1 or more" array axes

Currently, there is the * modifier to match "0 or more" axes. I think it would be very useful to have the closely related "1 or more" axes modifier, perhaps using +. For example:

Float[Array, "batch *features"] would match arrays with a batch dimension and any number of features, but also matches arrays with no feature axes.

Float[Array, "batch +features"] would only match arrays with a batch dimension and at least one more axis. So [b, a, b, c], [b, a], [b, 1] would all pass, but [b] would not.

Currently, this can be achieved by manually specifying that one differently named axis is present:

Float[Array, "batch feature0 *features"]

But I think it would be both more concise and clear with the + modifier.

Let me know if I'm missing anything with this idea, and thanks again for all your work on this package and the many others.

Start by tracing the existing * axis-modifier handling and the shape-matching tests that cover it. Use the examples in the issue to define the expected + behavior, with matching for one or more axes and rejection when no additional axis is present.