sort imports using isort. tested.

core/models/caves.py

@@ -1,33 +1,30 @@
-import string
-import os
 import datetime
-import re
 import json
-import subprocess
 import operator
-from datetime import datetime, timezone
-
+import os
+import re
+import string
+import subprocess
 from collections import defaultdict
+from datetime import datetime, timezone
 from pathlib import Path
-
 from urllib.parse import urljoin
 
-import settings
-
-from django.db import models
-from django.core.files.storage import FileSystemStorage
+from django.conf import settings
 from django.contrib.auth.models import User
 from django.contrib.contenttypes.models import ContentType
-from django.db.models import Min, Max
-from django.conf import settings
-from django.urls import reverse
-from django.template import Context, loader
+from django.core.files.storage import FileSystemStorage
+from django.db import models
+from django.db.models import Max, Min
 from django.shortcuts import render
+from django.template import Context, loader
+from django.urls import reverse
 
-from troggle.core.models.troggle import TroggleModel, Person, Expedition, DataIssue
+import settings
 from troggle.core.models.survex import SurvexStation
-from troggle.core.utils import writetrogglefile
-from troggle.core.utils import TROG
+from troggle.core.models.troggle import (DataIssue, Expedition, Person,
+                                         TroggleModel)
+from troggle.core.utils import TROG, writetrogglefile
 
 # Use the TROG global object to cache the cave lookup list. No good for multi-user..
 Gcavelookup = TROG['caves']['gcavelookup']