From 294c67503300b6bfa7785a5cfa55e25c1e452574 Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
Date: Thu, 22 Apr 2021 16:43:50 +0100
Subject: [PATCH] Remove `synapse.types.Collection` (#9856)

This is no longer required, since we have dropped support for Python 3.5.
---
 changelog.d/9856.misc                              |  1 +
 synapse/config/oidc.py                             |  4 ++--
 synapse/events/spamcheck.py                        |  3 +--
 synapse/federation/sender/__init__.py              | 14 ++++++++++++--
 synapse/handlers/appservice.py                     |  4 ++--
 synapse/handlers/device.py                         |  3 +--
 synapse/handlers/presence.py                       |  3 ++-
 synapse/handlers/sso.py                            |  3 ++-
 synapse/handlers/sync.py                           | 13 +++++++++++--
 synapse/notifier.py                                |  9 ++-------
 synapse/replication/tcp/protocol.py                |  3 +--
 synapse/state/__init__.py                          |  3 ++-
 synapse/state/v2.py                                |  3 ++-
 synapse/storage/_base.py                           |  4 ++--
 synapse/storage/database.py                        |  2 +-
 synapse/storage/databases/main/devices.py          |  4 ++--
 synapse/storage/databases/main/event_federation.py |  3 +--
 synapse/storage/databases/main/events_worker.py    | 13 +++++++++++--
 synapse/storage/databases/main/roommember.py       | 14 ++++++++++++--
 synapse/storage/databases/main/search.py           |  3 +--
 synapse/storage/databases/main/stream.py           |  4 ++--
 synapse/storage/persist_events.py                  |  3 +--
 synapse/storage/prepare_database.py                |  3 +--
 synapse/types.py                                   | 14 --------------
 synapse/util/caches/stream_change_cache.py         |  3 +--
 synapse/util/iterutils.py                          |  3 +--
 26 files changed, 77 insertions(+), 62 deletions(-)
 create mode 100644 changelog.d/9856.misc

diff --git a/changelog.d/9856.misc b/changelog.d/9856.misc
new file mode 100644
index 000000000..d67e8c386
--- /dev/null
+++ b/changelog.d/9856.misc
@@ -0,0 +1 @@
+Remove redundant `synapse.types.Collection` type definition.
diff --git a/synapse/config/oidc.py b/synapse/config/oidc.py
index 72402eb81..ea0abf5aa 100644
--- a/synapse/config/oidc.py
+++ b/synapse/config/oidc.py
@@ -14,14 +14,14 @@
 # limitations under the License.
 
 from collections import Counter
-from typing import Iterable, List, Mapping, Optional, Tuple, Type
+from typing import Collection, Iterable, List, Mapping, Optional, Tuple, Type
 
 import attr
 
 from synapse.config._util import validate_config
 from synapse.config.sso import SsoAttributeRequirement
 from synapse.python_dependencies import DependencyException, check_requirements
-from synapse.types import Collection, JsonDict
+from synapse.types import JsonDict
 from synapse.util.module_loader import load_module
 from synapse.util.stringutils import parse_and_validate_mxc_uri
 
diff --git a/synapse/events/spamcheck.py b/synapse/events/spamcheck.py
index c727b48c1..7118d5f52 100644
--- a/synapse/events/spamcheck.py
+++ b/synapse/events/spamcheck.py
@@ -15,12 +15,11 @@
 
 import inspect
 import logging
-from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple, Union
+from typing import TYPE_CHECKING, Any, Collection, Dict, List, Optional, Tuple, Union
 
 from synapse.rest.media.v1._base import FileInfo
 from synapse.rest.media.v1.media_storage import ReadableFileWrapper
 from synapse.spam_checker_api import RegistrationBehaviour
-from synapse.types import Collection
 from synapse.util.async_helpers import maybe_awaitable
 
 if TYPE_CHECKING:
diff --git a/synapse/federation/sender/__init__.py b/synapse/federation/sender/__init__.py
index b00a55324..022bbf7da 100644
--- a/synapse/federation/sender/__init__.py
+++ b/synapse/federation/sender/__init__.py
@@ -14,7 +14,17 @@
 
 import abc
 import logging
-from typing import TYPE_CHECKING, Dict, Hashable, Iterable, List, Optional, Set, Tuple
+from typing import (
+    TYPE_CHECKING,
+    Collection,
+    Dict,
+    Hashable,
+    Iterable,
+    List,
+    Optional,
+    Set,
+    Tuple,
+)
 
 from prometheus_client import Counter
 
@@ -31,7 +41,7 @@ from synapse.metrics import (
     events_processed_counter,
 )
 from synapse.metrics.background_process_metrics import run_as_background_process
-from synapse.types import Collection, JsonDict, ReadReceipt, RoomStreamToken
+from synapse.types import JsonDict, ReadReceipt, RoomStreamToken
 from synapse.util.metrics import Measure
 
 if TYPE_CHECKING:
diff --git a/synapse/handlers/appservice.py b/synapse/handlers/appservice.py
index d7bc4e23e..177310f0b 100644
--- a/synapse/handlers/appservice.py
+++ b/synapse/handlers/appservice.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-from typing import TYPE_CHECKING, Dict, List, Optional, Union
+from typing import TYPE_CHECKING, Collection, Dict, List, Optional, Union
 
 from prometheus_client import Counter
 
@@ -33,7 +33,7 @@ from synapse.metrics.background_process_metrics import (
     wrap_as_background_process,
 )
 from synapse.storage.databases.main.directory import RoomAliasMapping
-from synapse.types import Collection, JsonDict, RoomAlias, RoomStreamToken, UserID
+from synapse.types import JsonDict, RoomAlias, RoomStreamToken, UserID
 from synapse.util.metrics import Measure
 
 if TYPE_CHECKING:
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index c1d780098..34d39e3b4 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -14,7 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-from typing import TYPE_CHECKING, Dict, Iterable, List, Optional, Set, Tuple
+from typing import TYPE_CHECKING, Collection, Dict, Iterable, List, Optional, Set, Tuple
 
 from synapse.api import errors
 from synapse.api.constants import EventTypes
@@ -28,7 +28,6 @@ from synapse.api.errors import (
 from synapse.logging.opentracing import log_kv, set_tag, trace
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.types import (
-    Collection,
     JsonDict,
     StreamToken,
     UserID,
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index 598466c9b..7fd28ffa5 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -28,6 +28,7 @@ from bisect import bisect
 from contextlib import contextmanager
 from typing import (
     TYPE_CHECKING,
+    Collection,
     Dict,
     FrozenSet,
     Iterable,
@@ -59,7 +60,7 @@ from synapse.replication.tcp.commands import ClearUserSyncsCommand
 from synapse.replication.tcp.streams import PresenceFederationStream, PresenceStream
 from synapse.state import StateHandler
 from synapse.storage.databases.main import DataStore
-from synapse.types import Collection, JsonDict, UserID, get_domain_from_id
+from synapse.types import JsonDict, UserID, get_domain_from_id
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches.descriptors import _CacheContext, cached
 from synapse.util.metrics import Measure
diff --git a/synapse/handlers/sso.py b/synapse/handlers/sso.py
index 8d00ffdc7..044ff06d8 100644
--- a/synapse/handlers/sso.py
+++ b/synapse/handlers/sso.py
@@ -18,6 +18,7 @@ from typing import (
     Any,
     Awaitable,
     Callable,
+    Collection,
     Dict,
     Iterable,
     List,
@@ -40,7 +41,7 @@ from synapse.handlers.ui_auth import UIAuthSessionDataConstants
 from synapse.http import get_request_user_agent
 from synapse.http.server import respond_with_html, respond_with_redirect
 from synapse.http.site import SynapseRequest
-from synapse.types import Collection, JsonDict, UserID, contains_invalid_mxid_characters
+from synapse.types import JsonDict, UserID, contains_invalid_mxid_characters
 from synapse.util.async_helpers import Linearizer
 from synapse.util.stringutils import random_string
 
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index dc8ee8cd1..a9a3ee05c 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -14,7 +14,17 @@
 # limitations under the License.
 import itertools
 import logging
-from typing import TYPE_CHECKING, Any, Dict, FrozenSet, List, Optional, Set, Tuple
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Collection,
+    Dict,
+    FrozenSet,
+    List,
+    Optional,
+    Set,
+    Tuple,
+)
 
 import attr
 from prometheus_client import Counter
@@ -28,7 +38,6 @@ from synapse.push.clientformat import format_push_rules_for_user
 from synapse.storage.roommember import MemberSummary
 from synapse.storage.state import StateFilter
 from synapse.types import (
-    Collection,
     JsonDict,
     MutableStateMap,
     Requester,
diff --git a/synapse/notifier.py b/synapse/notifier.py
index d5ab77058..b9531007e 100644
--- a/synapse/notifier.py
+++ b/synapse/notifier.py
@@ -17,6 +17,7 @@ from collections import namedtuple
 from typing import (
     Awaitable,
     Callable,
+    Collection,
     Dict,
     Iterable,
     List,
@@ -42,13 +43,7 @@ from synapse.logging.opentracing import log_kv, start_active_span
 from synapse.logging.utils import log_function
 from synapse.metrics import LaterGauge
 from synapse.streams.config import PaginationConfig
-from synapse.types import (
-    Collection,
-    PersistedEventPosition,
-    RoomStreamToken,
-    StreamToken,
-    UserID,
-)
+from synapse.types import PersistedEventPosition, RoomStreamToken, StreamToken, UserID
 from synapse.util.async_helpers import ObservableDeferred, timeout_deferred
 from synapse.util.metrics import Measure
 from synapse.visibility import filter_events_for_client
diff --git a/synapse/replication/tcp/protocol.py b/synapse/replication/tcp/protocol.py
index 6860576e7..6e3705364 100644
--- a/synapse/replication/tcp/protocol.py
+++ b/synapse/replication/tcp/protocol.py
@@ -49,7 +49,7 @@ import fcntl
 import logging
 import struct
 from inspect import isawaitable
-from typing import TYPE_CHECKING, List, Optional
+from typing import TYPE_CHECKING, Collection, List, Optional
 
 from prometheus_client import Counter
 from zope.interface import Interface, implementer
@@ -76,7 +76,6 @@ from synapse.replication.tcp.commands import (
     ServerCommand,
     parse_command_from_line,
 )
-from synapse.types import Collection
 from synapse.util import Clock
 from synapse.util.stringutils import random_string
 
diff --git a/synapse/state/__init__.py b/synapse/state/__init__.py
index c7ee73115..b3bd92d37 100644
--- a/synapse/state/__init__.py
+++ b/synapse/state/__init__.py
@@ -19,6 +19,7 @@ from typing import (
     Any,
     Awaitable,
     Callable,
+    Collection,
     DefaultDict,
     Dict,
     FrozenSet,
@@ -46,7 +47,7 @@ from synapse.logging.utils import log_function
 from synapse.state import v1, v2
 from synapse.storage.databases.main.events_worker import EventRedactBehaviour
 from synapse.storage.roommember import ProfileInfo
-from synapse.types import Collection, StateMap
+from synapse.types import StateMap
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.metrics import Measure, measure_func
diff --git a/synapse/state/v2.py b/synapse/state/v2.py
index 32671ddbd..008644cd9 100644
--- a/synapse/state/v2.py
+++ b/synapse/state/v2.py
@@ -18,6 +18,7 @@ import logging
 from typing import (
     Any,
     Callable,
+    Collection,
     Dict,
     Generator,
     Iterable,
@@ -37,7 +38,7 @@ from synapse.api.constants import EventTypes
 from synapse.api.errors import AuthError
 from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
 from synapse.events import EventBase
-from synapse.types import Collection, MutableStateMap, StateMap
+from synapse.types import MutableStateMap, StateMap
 from synapse.util import Clock
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 56dd3a486..d472676ac 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -16,13 +16,13 @@
 import logging
 import random
 from abc import ABCMeta
-from typing import TYPE_CHECKING, Any, Iterable, Optional, Union
+from typing import TYPE_CHECKING, Any, Collection, Iterable, Optional, Union
 
 from synapse.storage.database import LoggingTransaction  # noqa: F401
 from synapse.storage.database import make_in_list_sql_clause  # noqa: F401
 from synapse.storage.database import DatabasePool
 from synapse.storage.types import Connection
-from synapse.types import Collection, StreamToken, get_domain_from_id
+from synapse.types import StreamToken, get_domain_from_id
 from synapse.util import json_decoder
 
 if TYPE_CHECKING:
diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index 9a6d2b21f..9452368bf 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -20,6 +20,7 @@ from time import monotonic as monotonic_time
 from typing import (
     Any,
     Callable,
+    Collection,
     Dict,
     Iterable,
     Iterator,
@@ -48,7 +49,6 @@ from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.storage.background_updates import BackgroundUpdater
 from synapse.storage.engines import BaseDatabaseEngine, PostgresEngine, Sqlite3Engine
 from synapse.storage.types import Connection, Cursor
-from synapse.types import Collection
 
 # python 3 does not have a maximum int value
 MAX_TXN_ID = 2 ** 63 - 1
diff --git a/synapse/storage/databases/main/devices.py b/synapse/storage/databases/main/devices.py
index b20487558..9be713399 100644
--- a/synapse/storage/databases/main/devices.py
+++ b/synapse/storage/databases/main/devices.py
@@ -15,7 +15,7 @@
 # limitations under the License.
 import abc
 import logging
-from typing import Any, Dict, Iterable, List, Optional, Set, Tuple
+from typing import Any, Collection, Dict, Iterable, List, Optional, Set, Tuple
 
 from synapse.api.errors import Codes, StoreError
 from synapse.logging.opentracing import (
@@ -31,7 +31,7 @@ from synapse.storage.database import (
     LoggingTransaction,
     make_tuple_comparison_clause,
 )
-from synapse.types import Collection, JsonDict, get_verify_key_from_cross_signing_key
+from synapse.types import JsonDict, get_verify_key_from_cross_signing_key
 from synapse.util import json_decoder, json_encoder
 from synapse.util.caches.descriptors import cached, cachedList
 from synapse.util.caches.lrucache import LruCache
diff --git a/synapse/storage/databases/main/event_federation.py b/synapse/storage/databases/main/event_federation.py
index 32ce70a39..ff81d5cd1 100644
--- a/synapse/storage/databases/main/event_federation.py
+++ b/synapse/storage/databases/main/event_federation.py
@@ -14,7 +14,7 @@
 import itertools
 import logging
 from queue import Empty, PriorityQueue
-from typing import Dict, Iterable, List, Set, Tuple
+from typing import Collection, Dict, Iterable, List, Set, Tuple
 
 from synapse.api.errors import StoreError
 from synapse.events import EventBase
@@ -25,7 +25,6 @@ from synapse.storage.databases.main.events_worker import EventsWorkerStore
 from synapse.storage.databases.main.signatures import SignatureWorkerStore
 from synapse.storage.engines import PostgresEngine
 from synapse.storage.types import Cursor
-from synapse.types import Collection
 from synapse.util.caches.descriptors import cached
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.iterutils import batch_iter
diff --git a/synapse/storage/databases/main/events_worker.py b/synapse/storage/databases/main/events_worker.py
index 64d70785b..2c823e09c 100644
--- a/synapse/storage/databases/main/events_worker.py
+++ b/synapse/storage/databases/main/events_worker.py
@@ -15,7 +15,16 @@
 import logging
 import threading
 from collections import namedtuple
-from typing import Container, Dict, Iterable, List, Optional, Tuple, overload
+from typing import (
+    Collection,
+    Container,
+    Dict,
+    Iterable,
+    List,
+    Optional,
+    Tuple,
+    overload,
+)
 
 from constantly import NamedConstant, Names
 from typing_extensions import Literal
@@ -45,7 +54,7 @@ from synapse.storage.database import DatabasePool
 from synapse.storage.engines import PostgresEngine
 from synapse.storage.util.id_generators import MultiWriterIdGenerator, StreamIdGenerator
 from synapse.storage.util.sequence import build_sequence_generator
-from synapse.types import Collection, JsonDict, get_domain_from_id
+from synapse.types import JsonDict, get_domain_from_id
 from synapse.util.caches.descriptors import cached
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.iterutils import batch_iter
diff --git a/synapse/storage/databases/main/roommember.py b/synapse/storage/databases/main/roommember.py
index fd525dce6..bd8513cd4 100644
--- a/synapse/storage/databases/main/roommember.py
+++ b/synapse/storage/databases/main/roommember.py
@@ -13,7 +13,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-from typing import TYPE_CHECKING, Dict, FrozenSet, Iterable, List, Optional, Set, Tuple
+from typing import (
+    TYPE_CHECKING,
+    Collection,
+    Dict,
+    FrozenSet,
+    Iterable,
+    List,
+    Optional,
+    Set,
+    Tuple,
+)
 
 from synapse.api.constants import EventTypes, Membership
 from synapse.events import EventBase
@@ -33,7 +43,7 @@ from synapse.storage.roommember import (
     ProfileInfo,
     RoomsForUser,
 )
-from synapse.types import Collection, PersistedEventPosition, get_domain_from_id
+from synapse.types import PersistedEventPosition, get_domain_from_id
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches import intern_string
 from synapse.util.caches.descriptors import _CacheContext, cached, cachedList
diff --git a/synapse/storage/databases/main/search.py b/synapse/storage/databases/main/search.py
index 0276f3065..6480d5a9f 100644
--- a/synapse/storage/databases/main/search.py
+++ b/synapse/storage/databases/main/search.py
@@ -15,7 +15,7 @@
 import logging
 import re
 from collections import namedtuple
-from typing import List, Optional, Set
+from typing import Collection, List, Optional, Set
 
 from synapse.api.errors import SynapseError
 from synapse.events import EventBase
@@ -23,7 +23,6 @@ from synapse.storage._base import SQLBaseStore, db_to_json, make_in_list_sql_cla
 from synapse.storage.database import DatabasePool
 from synapse.storage.databases.main.events_worker import EventRedactBehaviour
 from synapse.storage.engines import PostgresEngine, Sqlite3Engine
-from synapse.types import Collection
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/databases/main/stream.py b/synapse/storage/databases/main/stream.py
index db5ce4ea0..7581c7d3f 100644
--- a/synapse/storage/databases/main/stream.py
+++ b/synapse/storage/databases/main/stream.py
@@ -37,7 +37,7 @@ what sort order was used:
 import abc
 import logging
 from collections import namedtuple
-from typing import TYPE_CHECKING, Dict, List, Optional, Set, Tuple
+from typing import TYPE_CHECKING, Collection, Dict, List, Optional, Set, Tuple
 
 from twisted.internet import defer
 
@@ -53,7 +53,7 @@ from synapse.storage.database import (
 from synapse.storage.databases.main.events_worker import EventsWorkerStore
 from synapse.storage.engines import BaseDatabaseEngine, PostgresEngine
 from synapse.storage.util.id_generators import MultiWriterIdGenerator
-from synapse.types import Collection, PersistedEventPosition, RoomStreamToken
+from synapse.types import PersistedEventPosition, RoomStreamToken
 from synapse.util.caches.descriptors import cached
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 
diff --git a/synapse/storage/persist_events.py b/synapse/storage/persist_events.py
index 87e040b01..33dc752d8 100644
--- a/synapse/storage/persist_events.py
+++ b/synapse/storage/persist_events.py
@@ -17,7 +17,7 @@
 import itertools
 import logging
 from collections import deque, namedtuple
-from typing import Dict, Iterable, List, Optional, Set, Tuple
+from typing import Collection, Dict, Iterable, List, Optional, Set, Tuple
 
 from prometheus_client import Counter, Histogram
 
@@ -32,7 +32,6 @@ from synapse.storage.databases import Databases
 from synapse.storage.databases.main.events import DeltaState
 from synapse.storage.databases.main.events_worker import EventRedactBehaviour
 from synapse.types import (
-    Collection,
     PersistedEventPosition,
     RoomStreamToken,
     StateMap,
diff --git a/synapse/storage/prepare_database.py b/synapse/storage/prepare_database.py
index 05a935597..7a2cbee42 100644
--- a/synapse/storage/prepare_database.py
+++ b/synapse/storage/prepare_database.py
@@ -17,7 +17,7 @@ import logging
 import os
 import re
 from collections import Counter
-from typing import Generator, Iterable, List, Optional, TextIO, Tuple
+from typing import Collection, Generator, Iterable, List, Optional, TextIO, Tuple
 
 import attr
 from typing_extensions import Counter as CounterType
@@ -27,7 +27,6 @@ from synapse.storage.database import LoggingDatabaseConnection
 from synapse.storage.engines import BaseDatabaseEngine
 from synapse.storage.engines.postgres import PostgresEngine
 from synapse.storage.types import Cursor
-from synapse.types import Collection
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/types.py b/synapse/types.py
index 21654ae68..e19f28d54 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -15,13 +15,11 @@
 import abc
 import re
 import string
-import sys
 from collections import namedtuple
 from typing import (
     TYPE_CHECKING,
     Any,
     Dict,
-    Iterable,
     Mapping,
     MutableMapping,
     Optional,
@@ -50,18 +48,6 @@ if TYPE_CHECKING:
     from synapse.appservice.api import ApplicationService
     from synapse.storage.databases.main import DataStore
 
-# define a version of typing.Collection that works on python 3.5
-if sys.version_info[:3] >= (3, 6, 0):
-    from typing import Collection
-else:
-    from typing import Container, Sized
-
-    T_co = TypeVar("T_co", covariant=True)
-
-    class Collection(Iterable[T_co], Container[T_co], Sized):  # type: ignore
-        __slots__ = ()
-
-
 # Define a state map type from type/state_key to T (usually an event ID or
 # event)
 T = TypeVar("T")
diff --git a/synapse/util/caches/stream_change_cache.py b/synapse/util/caches/stream_change_cache.py
index 0469e7d12..e81e46889 100644
--- a/synapse/util/caches/stream_change_cache.py
+++ b/synapse/util/caches/stream_change_cache.py
@@ -14,11 +14,10 @@
 
 import logging
 import math
-from typing import Dict, FrozenSet, List, Mapping, Optional, Set, Union
+from typing import Collection, Dict, FrozenSet, List, Mapping, Optional, Set, Union
 
 from sortedcontainers import SortedDict
 
-from synapse.types import Collection
 from synapse.util import caches
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/util/iterutils.py b/synapse/util/iterutils.py
index 6f73b1d56..abfdc2983 100644
--- a/synapse/util/iterutils.py
+++ b/synapse/util/iterutils.py
@@ -15,6 +15,7 @@
 import heapq
 from itertools import islice
 from typing import (
+    Collection,
     Dict,
     Generator,
     Iterable,
@@ -26,8 +27,6 @@ from typing import (
     TypeVar,
 )
 
-from synapse.types import Collection
-
 T = TypeVar("T")