update extreme-self-casting to not require annotating self (#101)

* update extreme-self-casting to not require annotating `self`

* update question code to contain imports it uses

* update question code to contain imports it uses

* fix copy paste typo

challenges/extreme-self-casting/question.py

@@ -19,7 +19,7 @@ def transform_callable(self):
 
 
 ## End of your code ##
-from typing import assert_type
+from typing import assert_type, Any
 
 
 @Fn

challenges/extreme-self-casting/solution.py

@@ -10,25 +10,23 @@
 """
 
 
-from typing import Callable, Concatenate, ParamSpec, TypeVar, Generic, Any
+from typing import Callable, Concatenate, Generic, ParamSpec, TypeVar
 
-P = ParamSpec("P")
-R = TypeVar("R", covariant=True)
-VnCallable = TypeVar("VnCallable", bound=Callable)
 
+R = TypeVar('R')
+P = ParamSpec('P')
 
-class Fn(Generic[VnCallable]):
-    def __init__(self, f: VnCallable) -> None:
+
+class Fn(Generic[R, P]):
+    def __init__(self, f: Callable[P, R]):
         self.f = f
 
-    def transform_callable(
-        self: "Fn[Callable[P, R]]",
-    ) -> Callable[Concatenate[Any, P], R]:
+    def transform_callable(self) -> Callable[Concatenate[object, P], R]:
         ...
 
 
 ## End of your code ##
-from typing import assert_type
+from typing import assert_type, Any
 
 
 @Fn

challenges/extreme-self-casting/solution2.py

@@ -22,7 +22,7 @@ def transform_callable(self) -> Callable[Concatenate[Any, P], R]:
 
 
 ## End of your code ##
-from typing import assert_type
+from typing import assert_type, Any
 
 
 @Fn