'Convert longitude differential d_lon_coslat to d_lon.
Parameters
d_lon_coslat : `~astropy.units.Quantity`
Longitude differential that includes ``cos(lat)``.
base : instance of ``cls.base_representation``
The base from which the latitude will be taken.'

@classmethod
def _get_d_lon(cls, d_lon_coslat, base):

    cls._check_base(base)
    return (d_lon_coslat / np.cos(base.lat))
