python: Consistently use from…import for datetime.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zerver/lib/presence.py

@@ -1,6 +1,6 @@
-import datetime
 import time
 from collections import defaultdict
+from datetime import datetime, timedelta
 from typing import Any, Dict, Mapping, Optional, Sequence, Set
 
 from django.conf import settings
@@ -45,14 +45,14 @@ def get_presence_dicts_for_rows(
 
 
 def user_presence_datetime_with_date_joined_default(
-    dt: Optional[datetime.datetime], date_joined: datetime.datetime
-) -> datetime.datetime:
+    dt: Optional[datetime], date_joined: datetime
+) -> datetime:
     """
     Our data models support UserPresence objects not having None
     values for last_active_time/last_connected_time. The legacy API
     however has always sent timestamps, so for backward
     compatibility we cannot send such values through the API and need
-    to default to a sane datetime.
+    to default to a sane
 
     This helper functions expects to take a last_active_time or
     last_connected_time value and the date_joined of the user, which
@@ -65,7 +65,7 @@ def user_presence_datetime_with_date_joined_default(
 
 
 def get_modern_user_presence_info(
-    last_active_time: datetime.datetime, last_connected_time: datetime.datetime
+    last_active_time: datetime, last_connected_time: datetime
 ) -> Dict[str, Any]:
     # TODO: Do further bandwidth optimizations to this structure.
     result = {}
@@ -75,7 +75,7 @@ def get_modern_user_presence_info(
 
 
 def get_legacy_user_presence_info(
-    last_active_time: datetime.datetime, last_connected_time: datetime.datetime
+    last_active_time: datetime, last_connected_time: datetime
 ) -> Dict[str, Any]:
     """
     Reformats the modern UserPresence data structure so that legacy
@@ -106,7 +106,7 @@ def get_legacy_user_presence_info(
 
 
 def format_legacy_presence_dict(
-    last_active_time: datetime.datetime, last_connected_time: datetime.datetime
+    last_active_time: datetime, last_connected_time: datetime
 ) -> Dict[str, Any]:
     """
     This function assumes it's being called right after the presence object was updated,
@@ -114,7 +114,7 @@ def format_legacy_presence_dict(
     """
     if (
         last_active_time
-        + datetime.timedelta(seconds=settings.PRESENCE_LEGACY_EVENT_OFFSET_FOR_ACTIVITY_SECONDS)
+        + timedelta(seconds=settings.PRESENCE_LEGACY_EVENT_OFFSET_FOR_ACTIVITY_SECONDS)
         >= last_connected_time
     ):
         status = UserPresence.LEGACY_STATUS_ACTIVE
@@ -154,7 +154,7 @@ def get_presence_for_user(
 def get_presence_dict_by_realm(
     realm: Realm, slim_presence: bool = False, requesting_user_profile: Optional[UserProfile] = None
 ) -> Dict[str, Dict[str, Any]]:
-    two_weeks_ago = timezone_now() - datetime.timedelta(weeks=2)
+    two_weeks_ago = timezone_now() - timedelta(weeks=2)
     query = UserPresence.objects.filter(
         realm_id=realm.id,
         last_connected_time__gte=two_weeks_ago,