Issue #10750: The `raw` attribute of buffered IO objects is now read-only.
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index f7e34a8..55c0a23 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -1541,7 +1541,7 @@
 };
 
 static PyMemberDef bufferedreader_members[] = {
-    {"raw", T_OBJECT, offsetof(buffered, raw), 0},
+    {"raw", T_OBJECT, offsetof(buffered, raw), READONLY},
     {NULL}
 };
 
@@ -1926,7 +1926,7 @@
 };
 
 static PyMemberDef bufferedwriter_members[] = {
-    {"raw", T_OBJECT, offsetof(buffered, raw), 0},
+    {"raw", T_OBJECT, offsetof(buffered, raw), READONLY},
     {NULL}
 };
 
@@ -2320,7 +2320,7 @@
 };
 
 static PyMemberDef bufferedrandom_members[] = {
-    {"raw", T_OBJECT, offsetof(buffered, raw), 0},
+    {"raw", T_OBJECT, offsetof(buffered, raw), READONLY},
     {NULL}
 };