Fix type annotation in pandas. version (#25949)

Author: vaibhavhrt

mypy.ini

@@ -5,9 +5,6 @@ follow_imports=silent
 [mypy-pandas.conftest,pandas.tests.*]
 ignore_errors=True
 
-[mypy-pandas._version]
-ignore_errors=True
-
 [mypy-pandas.compat]
 ignore_errors=True
 

pandas/_version.py

@@ -12,6 +12,7 @@
 import re
 import subprocess
 import sys
+from typing import Callable, Dict
 
 from pandas.compat import PY3
 
@@ -48,12 +49,11 @@ class NotThisMethod(Exception):
     pass
 
 
-LONG_VERSION_PY = {}
-HANDLERS = {}
+HANDLERS = {}  # type: Dict[str, Dict[str, Callable]]
 
 
-def register_vcs_handler(vcs, method):  # decorator
-    def decorate(f):
+def register_vcs_handler(vcs: str, method: str) -> Callable:  # decorator
+    def decorate(f: Callable) -> Callable:
         if vcs not in HANDLERS:
             HANDLERS[vcs] = {}
         HANDLERS[vcs][method] = f