bpo-35397: Remove deprecation and document urllib.parse.unwrap (GH-11481)

diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index dfba704..daefb20 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -979,17 +979,15 @@
 
 
 def unwrap(url):
-    warnings.warn("urllib.parse.unwrap() is deprecated as of 3.8",
-                  DeprecationWarning, stacklevel=2)
-    return _unwrap(url)
+    """Transform a string like '<URL:scheme://host/path>' into 'scheme://host/path'.
 
-
-def _unwrap(url):
-    """unwrap('<URL:type://host/path>') --> 'type://host/path'."""
+    The string is returned unchanged if it's not a wrapped URL.
+    """
     url = str(url).strip()
     if url[:1] == '<' and url[-1:] == '>':
         url = url[1:-1].strip()
-    if url[:4] == 'URL:': url = url[4:].strip()
+    if url[:4] == 'URL:':
+        url = url[4:].strip()
     return url