I've decided to test `typing.py` with `cosmic-ray` mutation testing framework. It identified 3 potential problems.

Config:

```
[cosmic-ray]
module-path = "Lib/typing.py"
timeout = 15.0
excluded-modules = []
test-command = "./python.exe -m test -v test_typing --failfast"

[cosmic-ray.distributor]
name = "local"
```

Repro steps:
0. pip install cosmic-ray
1. Copy config above as `typing.toml`
2. cosmic-ray init typing.toml typing.sqlite
3. cosmic-ray exec tutorial.toml tutorial.sqlite 

Survived mutants:

1. ```
--- mutation diff ---
--- aLib/typing.py
+++ bLib/typing.py
@@ -1103,7 +1103,7 @@
             if Protocol in bases:
                 return ()
             i = bases.index(self)
-            for b in bases[i+1:]:
+            for b in bases[i*1:]:
                 if isinstance(b, _BaseGenericAlias) and b is not self:
                     return ()
         return (self.__origin__,)
```

2. ```
--- mutation diff ---
--- aLib/typing.py
+++ bLib/typing.py
@@ -1103,7 +1103,7 @@
             if Protocol in bases:
                 return ()
             i = bases.index(self)
-            for b in bases[i+1:]:
+            for b in bases[i//1:]:
                 if isinstance(b, _BaseGenericAlias) and b is not self:
                     return ()
         return (self.__origin__,)
```

3. ```
--- mutation diff ---
--- aLib/typing.py
+++ bLib/typing.py
@@ -1103,7 +1103,7 @@
             if Protocol in bases:
                 return ()
             i = bases.index(self)
-            for b in bases[i+1:]:
+            for b in bases[i**1:]:
                 if isinstance(b, _BaseGenericAlias) and b is not self:
                     return ()
         return (self.__origin__,)
```

I've attached the full report to this issue if it is interesting to anyone: https://gist.github.com/sobolevn/79f1729dcf0b8c4b2a9bcee67027673a