bpo-39939: Add str.removeprefix and str.removesuffix (GH-18939)

Added str.removeprefix and str.removesuffix methods and corresponding
bytes, bytearray, and collections.UserString methods to remove affixes
from a string if present. See PEP 616 for a full description.

1 files changed, 8 insertions, 0 deletions

diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index e19840650dd..bb9a605a994 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -1239,6 +1239,14 @@ class UserString(_collections_abc.Sequence):
         if isinstance(sub, UserString):
             sub = sub.data
         return self.data.count(sub, start, end)
+    def removeprefix(self, prefix, /):
+        if isinstance(prefix, UserString):
+            prefix = prefix.data
+        return self.__class__(self.data.removeprefix(prefix))
+    def removesuffix(self, suffix, /):
+        if isinstance(suffix, UserString):
+            suffix = suffix.data
+        return self.__class__(self.data.removesuffix(suffix))
     def encode(self, encoding='utf-8', errors='strict'):
         encoding = 'utf-8' if encoding is None else encoding
         errors = 'strict' if errors is None else errors