Fix mypy and line-too-long errors (#3313)

pyro/poutine/indep_messenger.py

@@ -24,11 +24,11 @@ def vectorized(self) -> bool:
         return self.dim is not None
 
     def _key(self) -> Tuple[str, Optional[int], int, int]:
+        size = self.size
         with ignore_jit_warnings(["Converting a tensor to a Python number"]):
-            size = (
-                self.size.item() if isinstance(self.size, torch.Tensor) else self.size  # type: ignore[attr-defined, unreachable]
-            )
-            return self.name, self.dim, size, self.counter
+            if isinstance(size, torch.Tensor):  # type: ignore[unreachable]
+                size = size.item()  # type: ignore[unreachable]
+        return self.name, self.dim, size, self.counter
 
     def __eq__(self, other: object) -> bool:
         if not isinstance(other, CondIndepStackFrame):

pyro/poutine/runtime.py

@@ -351,7 +351,7 @@ def _fn(
         if not am_i_wrapped():
             return fn(*args, **kwargs)
         else:
-            msg = Message[_P, _T](
+            msg = Message(
                 type=type,
                 name=name,
                 fn=fn,