first version finished

django/utils/baseconv.pyi

@@ -0,0 +1,10 @@
+from typing import (
+    Tuple,
+    Union,
+)
+
+
+class BaseConverter:
+    def convert(self, number: Union[str, int], from_digits: str, to_digits: str, sign: str) -> Tuple[int, str]: ...
+    def decode(self, s: str) -> int: ...
+    def encode(self, i: int) -> str: ...