make a module for typing-related things

babi/_types.py

@@ -0,0 +1,6 @@
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from typing import Protocol  # python3.8+
+else:
+    Protocol = object

babi/list_spy.py

@@ -2,12 +2,8 @@ import functools
 from typing import Callable
 from typing import Iterator
 from typing import List
-from typing import TYPE_CHECKING
 
-if TYPE_CHECKING:
-    from typing import Protocol  # python3.8+
-else:
-    Protocol = object
+from babi._types import Protocol
 
 
 class MutableSequenceNoSlice(Protocol):

tests/features/conftest.py

@@ -5,21 +5,16 @@ import shlex
 import sys
 from typing import List
 from typing import NamedTuple
-from typing import TYPE_CHECKING
 from typing import Union
 from unittest import mock
 
 import pytest
 
+from babi._types import Protocol
 from babi.main import main
 from babi.screen import VERSION_STR
 from testing.runner import PrintsErrorRunner
 
-if TYPE_CHECKING:
-    from typing import Protocol
-else:
-    Protocol = object
-
 
 @pytest.fixture(autouse=True)
 def xdg_data_home(tmpdir):