Format option group kwargs into canonical options format

def _group_kwargs_to_options(cls, obj, kwargs):
        "Format option group kwargs into canonical options format"
        groups = Options._option_groups
        if set(kwargs.keys()) - set(groups):
            raise Exception("Keyword options %s must be one of  %s" % (groups,
                            ','.join(repr(g) for g in groups)))
        elif not all(isinstance(v, dict) for v in kwargs.values()):
            raise Exception("The %s options must be specified using dictionary groups" %
                            ','.join(repr(k) for k in kwargs.keys()))

        # Check whether the user is specifying targets (such as 'Image.Foo')
        targets = [grp and all(k[0].isupper() for k in grp) for grp in kwargs.values()]
        if any(targets) and not all(targets):
            raise Exception("Cannot mix target specification keys such as 'Image' with non-target keywords.")
        elif not any(targets):
            # Not targets specified - add current object as target
            sanitized_group = util.group_sanitizer(obj.group)
            if obj.label:
                identifier = ('%s.%s.%s' % (
                    obj.__class__.__name__, sanitized_group,
                    util.label_sanitizer(obj.label)))
            elif  sanitized_group != obj.__class__.__name__:
                identifier = '%s.%s' % (obj.__class__.__name__, sanitized_group)
            else:
                identifier = obj.__class__.__name__

            options = {identifier:{grp:kws for (grp,kws) in kwargs.items()}}
        else:
            dfltdict = defaultdict(dict)
            for grp, entries in kwargs.items():
                for identifier, kws in entries.items():
                    dfltdict[identifier][grp] = kws
            options = dict(dfltdict)
        return options