typing: 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 two fixes for use-before-define
issues:

-    def set_zulip_client(self, zulipToJabberClient: ZulipToJabberBot) -> None:
+    def set_zulip_client(self, zulipToJabberClient: 'ZulipToJabberBot') -> None:

-def init_from_options(options: Any, client: Optional[str] = None) -> Client:
+def init_from_options(options: Any, client: Optional[str] = None) -> 'Client':

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

zulip/integrations/bridge_with_irc/irc_mirror_backend.py

@@ -9,9 +9,8 @@ from typing import Any, Dict
 class IRCBot(irc.bot.SingleServerIRCBot):
     reactor_class = AioReactor
 
-    def __init__(self, zulip_client, stream, topic, channel,
-                 nickname, server, nickserv_password='', port=6667):
-        # type: (Any, str, str, irc.bot.Channel, str, str, str, int) -> None
+    def __init__(self, zulip_client: Any, stream: str, topic: str, channel: irc.bot.Channel,
+                 nickname: str, server: str, nickserv_password: str = '', port: int = 6667) -> None:
         self.channel = channel  # type: irc.bot.Channel
         self.zulip_client = zulip_client
         self.stream = stream
@@ -23,13 +22,11 @@ class IRCBot(irc.bot.SingleServerIRCBot):
         # Initialize IRC bot after proper connection to Zulip server has been confirmed.
         irc.bot.SingleServerIRCBot.__init__(self, [(server, port)], nickname, nickname)
 
-    def zulip_sender(self, sender_string):
-        # type: (str) -> str
+    def zulip_sender(self, sender_string: str) -> str:
         nick = sender_string.split("!")[0]
         return nick + "@" + self.IRC_DOMAIN
 
-    def connect(self, *args, **kwargs):
-        # type: (*Any, **Any) -> None
+    def connect(self, *args: Any, **kwargs: Any) -> None:
         # Taken from
         # https://github.com/jaraco/irc/blob/master/irc/client_aio.py,
         # in particular the method of AioSimpleIRCClient
@@ -38,8 +35,7 @@ class IRCBot(irc.bot.SingleServerIRCBot):
         )
         print("Listening now. Please send an IRC message to verify operation")
 
-    def check_subscription_or_die(self):
-        # type: () -> None
+    def check_subscription_or_die(self) -> None:
         resp = self.zulip_client.list_subscriptions()
         if resp["result"] != "success":
             print("ERROR: %s" % (resp["msg"],))
@@ -49,19 +45,16 @@ class IRCBot(irc.bot.SingleServerIRCBot):
             print("The bot is not yet subscribed to stream '%s'. Please subscribe the bot to the stream first." % (self.stream,))
             exit(1)
 
-    def on_nicknameinuse(self, c, e):
-        # type: (ServerConnection, Event) -> None
+    def on_nicknameinuse(self, c: ServerConnection, e: Event) -> None:
         c.nick(c.get_nickname().replace("_zulip", "__zulip"))
 
-    def on_welcome(self, c, e):
-        # type: (ServerConnection, Event) -> None
+    def on_welcome(self, c: ServerConnection, e: Event) -> None:
         if len(self.nickserv_password) > 0:
             msg = 'identify %s' % (self.nickserv_password,)
             c.privmsg('NickServ', msg)
         c.join(self.channel)
 
-        def forward_to_irc(msg):
-            # type: (Dict[str, Any]) -> None
+        def forward_to_irc(msg: Dict[str, Any]) -> None:
             not_from_zulip_bot = msg["sender_email"] != self.zulip_client.email
             if not not_from_zulip_bot:
                 # Do not forward echo
@@ -88,8 +81,7 @@ class IRCBot(irc.bot.SingleServerIRCBot):
         z2i = mp.Process(target=self.zulip_client.call_on_each_message, args=(forward_to_irc,))
         z2i.start()
 
-    def on_privmsg(self, c, e):
-        # type: (ServerConnection, Event) -> None
+    def on_privmsg(self, c: ServerConnection, e: Event) -> None:
         content = e.arguments[0]
         sender = self.zulip_sender(e.source)
         if sender.endswith("_zulip@" + self.IRC_DOMAIN):
@@ -103,8 +95,7 @@ class IRCBot(irc.bot.SingleServerIRCBot):
             "content": content,
         }))
 
-    def on_pubmsg(self, c, e):
-        # type: (ServerConnection, Event) -> None
+    def on_pubmsg(self, c: ServerConnection, e: Event) -> None:
         content = e.arguments[0]
         sender = self.zulip_sender(e.source)
         if sender.endswith("_zulip@" + self.IRC_DOMAIN):
@@ -119,12 +110,10 @@ class IRCBot(irc.bot.SingleServerIRCBot):
             "content": "**{}**: {}".format(sender, content),
         }))
 
-    def on_dccmsg(self, c, e):
-        # type: (ServerConnection, Event) -> None
+    def on_dccmsg(self, c: ServerConnection, e: Event) -> None:
         c.privmsg("You said: " + e.arguments[0])
 
-    def on_dccchat(self, c, e):
-        # type: (ServerConnection, Event) -> None
+    def on_dccchat(self, c: ServerConnection, e: Event) -> None:
         if len(e.arguments) != 2:
             return
         args = e.arguments[1].split()