As of NumPy 1.15, NumPy's generalized ufuncs now support axis/axes/keepdims arguments:
https://docs.scipy.org/doc/numpy/release.html#generalized-ufuncs-now-accept-axes-axis-and-keepdims-arguments

It would be nice to support these in dask.array.apply_gufunc(), too. This would be useful for implementing functions like median (#3819).