def occipital_flatmap(cortex, radius=None):
mdl = retinotopy_model('<STR_LIT>', hemi=cortex.chirality)<EOL>mp = mdl.map_projection<EOL>if radius is not None: mp = mp.copy(radius=radius)<EOL>return mp(cortex)<EOL>
occipital_flatmap(cortex) yields a flattened mesh of the occipital cortex of the given cortex
  object.

Note that if the cortex is not registrered to fsaverage, this will fail.

The option radius may be given to specify the fraction of the cortical sphere (in radians) to
include in the map.