added type annotation and minor docstring changes

Author: Khemkaran

pandas/core/arrays/_arrow_string_mixins.py

@@ -304,7 +304,7 @@ def _str_contains(
 
     def _str_match(
         self,
-        pat,
+        pat: str | re.Pattern,
         case: bool = True,
         flags: int = 0,
         na: Scalar | lib.NoDefault = lib.no_default,

pandas/core/strings/accessor.py

@@ -1361,7 +1361,7 @@ def match(self, pat: str, case: bool = True, flags: int = 0, na=lib.no_default):
 
         Parameters
         ----------
-        pat : str
+        pat : str or compiled regex
             Character sequence or regular expression.
         case : bool, default True
             If True, case sensitive.

pandas/core/strings/object_array.py

@@ -248,7 +248,7 @@ def rep(x, r):
 
     def _str_match(
         self,
-        pat,
+        pat: str | re.Pattern,
         case: bool = True,
         flags: int = 0,
         na: Scalar | lib.NoDefault = lib.no_default,