def disk_vmag(hemi, retinotopy='<STR_LIT>', to=None, **kw):
mdat = mag_data(hemi, retinotopy=retinotopy, **kw)<EOL>if pimms.is_vector(mdat): return tuple([face_vmag(m, to=to) for m in mdat])<EOL>elif pimms.is_vector(mdat.keys(), '<STR_LIT:int>'):<EOL><INDENT>return pimms.lazy_map({k: curry(lambda k: face_vmag(mdat[k], to=to), k)<EOL>for k in six.iterkeys(mdat)})<EOL><DEDENT>raise NotImplementedError()<EOL>
disk_vmag(mesh) yields the visual magnification based on the projection of disks on the cortical
  surface into the visual field.

All options accepted by mag_data() are accepted by disk_vmag().