mypy: Add stubs for zephyr.

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

stubs/_zephyr.pyi

@@ -0,0 +1,65 @@
+from typing import List, Optional, Sequence, Tuple, overload
+
+from typing_extensions import Literal
+
+class ZUid:
+    address: str
+    time: float
+
+class ZNotice:
+    kind: int
+    cls: str
+    instance: str
+    uid: ZUid
+    time: int
+    port: int
+    auth: bool
+    recipient: Optional[str]
+    sender: Optional[str]
+    opcode: Optional[str]
+    format: str
+    other_fields: List[str]
+    fields: List[str]
+    _charset: Optional[str]
+    def __init__(
+        self,
+        kind: int = ...,
+        cls: str = ...,
+        instance: str = ...,
+        uid: ZUid = ...,
+        time: int = ...,
+        port: int = ...,
+        auth: bool = ...,
+        recipient: Optional[str] = ...,
+        sender: Optional[str] = ...,
+        opcode: Optional[str] = ...,
+        format: str = ...,
+        other_fields: List[str] = ...,
+        fields: List[str] = ...,
+        _charset: Optional[str] = ...,
+        message: str = ...,
+    ): ...
+    def getmessage(self) -> str: ...
+    def setmessage(self, newmsg: str) -> None: ...
+    message = property(getmessage, setmessage)
+    @property
+    def charset(self) -> Optional[str]: ...
+    def send(self) -> None: ...
+
+def initialize() -> None: ...
+def openPort() -> int: ...
+def getFD() -> int: ...
+def setFD(fd: int) -> None: ...
+def sub(cls: str, instance: str, recipient: str) -> None: ...
+def subAll(lst: Sequence[Tuple[str, str, str]]) -> None: ...
+def unsub(cls: str, instance: str, recipient: str) -> None: ...
+def cancelSubs() -> None: ...
+@overload
+def receive(block: Literal[True]) -> ZNotice: ...
+@overload
+def receive(block: bool = ...) -> Optional[ZNotice]: ...
+def sender() -> str: ...
+def realm() -> str: ...
+def dump_session() -> bytes: ...
+def load_session(session: bytes) -> None: ...
+def getSubscriptions() -> List[Tuple[str, str, str]]: ...

stubs/zephyr.pyi

@@ -0,0 +1,13 @@
+from typing import Set, Tuple
+
+import _zephyr
+from _zephyr import ZNotice as ZNotice
+from _zephyr import receive as receive
+
+_z = _zephyr
+__inited: bool
+
+def init() -> None: ...
+
+class Subscriptions(Set[Tuple[str, str, str]]):
+    pass