There are duplicate functions in coordinates.py.
Line 702 - extra _xyz_to_lonlat_rad
Line 752 - extra _xyz_to_lonlat_rad_no_norm
Line 793 - extra _lonlat_rad_to_xyz
Line 806 - extra _xyz_to_lonlat_deg
Line 843 - extra _normalize_xyz_scalar

Also, typo in comment on Lines 57 & 133: [0, pi] should be [0, 2*pi]

And, spelling mistake in comment on Line 185: cartesiain