Add StateMap type alias (#6715)

synapse/types.py

@@ -17,6 +17,7 @@ import re
 import string
 import sys
 from collections import namedtuple
+from typing import Dict, Tuple, TypeVar
 
 import attr
 from signedjson.key import decode_verify_key_bytes
@@ -28,7 +29,7 @@ from synapse.api.errors import SynapseError
 if sys.version_info[:3] >= (3, 6, 0):
     from typing import Collection
 else:
-    from typing import Sized, Iterable, Container, TypeVar
+    from typing import Sized, Iterable, Container
 
     T_co = TypeVar("T_co", covariant=True)
 
@@ -36,6 +37,12 @@ else:
         __slots__ = ()
 
 
+# Define a state map type from type/state_key to T (usually an event ID or
+# event)
+T = TypeVar("T")
+StateMap = Dict[Tuple[str, str], T]
+
+
 class Requester(
     namedtuple(
         "Requester", ["user", "access_token_id", "is_guest", "device_id", "app_service"]