clean up TYPE_CHECKING imports

.coveragerc

@@ -30,3 +30,4 @@ exclude_lines =
     # Don't complain if non-runnable code isn't run:
     ^if __name__ == ['"]__main__['"]:$
     ^\s*if False:
+    ^\s*if TYPE_CHECKING:

src/flake8/__init__.py

@@ -11,9 +11,7 @@ This module
 """
 import logging
 import sys
-
-if False:  # `typing.TYPE_CHECKING` was introduced in 3.5.2
-    from typing import Type  # `typing.Type` was introduced in 3.5.2
+from typing import Type
 
 LOG = logging.getLogger(__name__)
 LOG.addHandler(logging.NullHandler())

src/flake8/formatting/base.py

@@ -4,8 +4,9 @@ from typing import IO
 from typing import List
 from typing import Optional
 from typing import Tuple
+from typing import TYPE_CHECKING
 
-if False:  # `typing.TYPE_CHECKING` was introduced in 3.5.2
+if TYPE_CHECKING:
     from flake8.statistics import Statistics
     from flake8.style_guide import Violation
 

src/flake8/formatting/default.py

@@ -1,10 +1,11 @@
 """Default formatting class for Flake8."""
 from typing import Optional
 from typing import Set
+from typing import TYPE_CHECKING
 
 from flake8.formatting import base
 
-if False:  # `typing.TYPE_CHECKING` was introduced in 3.5.2
+if TYPE_CHECKING:
     from flake8.style_guide import Violation
 
 

src/flake8/main/application.py

@@ -8,6 +8,8 @@ from typing import List
 from typing import Optional
 from typing import Set
 from typing import Tuple
+from typing import Type
+from typing import TYPE_CHECKING
 
 import flake8
 from flake8 import checker
@@ -21,9 +23,7 @@ from flake8.options import config
 from flake8.options import manager
 from flake8.plugins import manager as plugin_manager
 
-if False:  # `typing.TYPE_CHECKING` was introduced in 3.5.2
-    from typing import Type  # `typing.Type` was introduced in 3.5.2
-
+if TYPE_CHECKING:
     from flake8.formatting.base import BaseFormatter
 
 

src/flake8/options/manager.py

@@ -16,12 +16,14 @@ from typing import Optional
 from typing import Sequence
 from typing import Set
 from typing import Tuple
+from typing import Type
+from typing import TYPE_CHECKING
 from typing import Union
 
 from flake8 import utils
 
-if False:  # TYPE_CHECKING
-    from typing import NoReturn, Type
+if TYPE_CHECKING:
+    from typing import NoReturn
 
 LOG = logging.getLogger(__name__)
 

src/flake8/statistics.py

@@ -4,8 +4,9 @@ from typing import Dict
 from typing import Generator
 from typing import List
 from typing import Optional
+from typing import TYPE_CHECKING
 
-if False:  # `typing.TYPE_CHECKING` was introduced in 3.5.2
+if TYPE_CHECKING:
     from flake8.style_guide import Violation
 
 

src/flake8/utils.py

@@ -19,11 +19,12 @@ from typing import Pattern
 from typing import Sequence
 from typing import Set
 from typing import Tuple
+from typing import TYPE_CHECKING
 from typing import Union
 
 from flake8 import exceptions
 
-if False:  # `typing.TYPE_CHECKING` was introduced in 3.5.2
+if TYPE_CHECKING:
     from flake8.plugins.manager import Plugin
 
 DIFF_HUNK_REGEXP = re.compile(r"^@@ -\d+(?:,\d+)? \+(\d+)(?:,(\d+))? @@.*$")