diff --git a/bookwyrm/models/group.py b/bookwyrm/models/group.py
index c2dfcb06..8fab4472 100644
--- a/bookwyrm/models/group.py
+++ b/bookwyrm/models/group.py
@@ -1,6 +1,6 @@
 """ do book related things with other users """
 from django.apps import apps
-from django.db import models, IntegrityError, models, transaction
+from django.db import models, IntegrityError, transaction
 from django.db.models import Q
 from bookwyrm.settings import DOMAIN
 from .base_model import BookWyrmModel
@@ -36,6 +36,7 @@ class GroupMember(models.Model):
     )
 
     class Meta:
+        """Users can only have one membership per group"""
         constraints = [
             models.UniqueConstraint(fields=["group", "user"], name="unique_membership")
         ]
@@ -83,6 +84,7 @@ class GroupMemberInvitation(models.Model):
     )
 
     class Meta:
+        """Users can only have one outstanding invitation per group"""
         constraints = [
             models.UniqueConstraint(fields=["group", "user"], name="unique_invitation")
         ]
diff --git a/bookwyrm/models/list.py b/bookwyrm/models/list.py
index 46d57c2d..8a083b69 100644
--- a/bookwyrm/models/list.py
+++ b/bookwyrm/models/list.py
@@ -1,16 +1,15 @@
 """ make a list of books!! """
-from bookwyrm.models.group import GroupMember
-from dataclasses import field
 from django.apps import apps
 from django.db import models
 from django.utils import timezone
 
 from bookwyrm import activitypub
 from bookwyrm.settings import DOMAIN
+
 from .activitypub_mixin import CollectionItemMixin, OrderedCollectionMixin
 from .base_model import BookWyrmModel
-from . import fields
 from .group import GroupMember
+from . import fields
 
 CurationType = models.TextChoices(
     "Curation",