export_sets.py

import pymel.core as pm

default = ['TurtleDefaultBakeLayer','defaultLightSet','defaultObjectSet','initialParticleSE','initialShadingGroup']

set_list = [x for x in pm.ls(type="objectSet") if x.name() not in default]

cmd_list = []

for set in set_list:
    if set.isReferenced() is True:
        continue
    object = set.elements()
    if len(object) != 0:
        cmd_list.append("select -r " + " ".join([x.name() for x in object]) + ";")
        cmd_list.append('sets -name "{0}";'.format(set.name()))
        
cmd_list.append("select -cl;")

save_file = pm.fileDialog(m=1,dm="*.mel")

if save_file is not None:
    with open(save_file,'w') as f:
        f.write("\n".join(cmd_list))