python: Convert function type annotations to Python 3 style.

Generated by com2ann (slightly patched to avoid also converting
assignment type annotations, which require Python 3.6), followed by
some manual whitespace adjustment, and six fixes for runtime issues:

-    def __init__(self, token: Token, parent: Optional[Node]) -> None:
+    def __init__(self, token: Token, parent: "Optional[Node]") -> None:

-def main(options: argparse.Namespace) -> NoReturn:
+def main(options: argparse.Namespace) -> "NoReturn":

-def fetch_request(url: str, callback: Any, **kwargs: Any) -> Generator[Callable[..., Any], Any, None]:
+def fetch_request(url: str, callback: Any, **kwargs: Any) -> "Generator[Callable[..., Any], Any, None]":

-def assert_server_running(server: subprocess.Popen[bytes], log_file: Optional[str]) -> None:
+def assert_server_running(server: "subprocess.Popen[bytes]", log_file: Optional[str]) -> None:

-def server_is_up(server: subprocess.Popen[bytes], log_file: Optional[str]) -> bool:
+def server_is_up(server: "subprocess.Popen[bytes]", log_file: Optional[str]) -> bool:

-    method_kwarg_pairs: List[FuncKwargPair],
+    method_kwarg_pairs: "List[FuncKwargPair]",

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

tools/lib/html_grep.py

@@ -3,8 +3,7 @@ from typing import Dict, List, Set
 
 from .html_branches import html_branches, HtmlTreeBranch
 
-def show_all_branches(fns):
-    # type: (List[str]) -> None
+def show_all_branches(fns: List[str]) -> None:
     for fn in fns:
         print(fn)
         with open(fn) as f:
@@ -21,8 +20,7 @@ class Grepper:
     HtmlTreeBranch objects.
     '''
 
-    def __init__(self, fns):
-        # type: (List[str]) -> None
+    def __init__(self, fns: List[str]) -> None:
         all_branches = []  # type: List[HtmlTreeBranch]
 
         for fn in fns:
@@ -38,8 +36,7 @@ class Grepper:
 
         self.all_branches = set(all_branches)
 
-    def grep(self, word_set):
-        # type: (Set[str]) -> None
+    def grep(self, word_set: Set[str]) -> None:
 
         words = list(word_set)  # type: List[str]
 
@@ -57,7 +54,6 @@ class Grepper:
             print(branch.staircase_text())
             print('')
 
-def grep(fns, words):
-    # type: (List[str], Set[str]) -> None
+def grep(fns: List[str], words: Set[str]) -> None:
     grepper = Grepper(fns)
     grepper.grep(words)