Fix type hints and small bugs

none/session.py

@@ -1,25 +1,21 @@
-from typing import Union, Callable, Dict, Any, List, Sequence
-
 from . import NoneBot
 from .helpers import send, send_expr
+from .typing import Context_T, Message_T, Expression_T
 
 
 class BaseSession:
     __slots__ = ('bot', 'ctx')
 
-    def __init__(self, bot: NoneBot, ctx: Dict[str, Any]):
+    def __init__(self, bot: NoneBot, ctx: Context_T):
         self.bot = bot
         self.ctx = ctx
 
-    async def send(self,
-                   message: Union[str, Dict[str, Any], List[Dict[str, Any]]],
-                   *, ignore_failure: bool = True) -> None:
+    async def send(self, message: Message_T, *,
+                   ignore_failure: bool = True) -> None:
         """Send a message ignoring failure by default."""
         return await send(self.bot, self.ctx, message,
                           ignore_failure=ignore_failure)
 
-    async def send_expr(self,
-                        expr: Union[str, Sequence[str], Callable],
-                        **kwargs):
+    async def send_expr(self, expr: Expression_T, **kwargs):
         """Sending a expression message ignoring failure by default."""
         return await send_expr(self.bot, self.ctx, expr, **kwargs)