Issue #15571: comment the fact what python impl of TextIOWrapper always works in write_throuth mode
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index 1ce61e9..387c585 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -1461,6 +1461,9 @@
_CHUNK_SIZE = 2048
+ # The write_through argument has no effect here since this
+ # implementation always writes through. The argument is present only
+ # so that the signature can match the signature of the C version.
def __init__(self, buffer, encoding=None, errors=None, newline=None,
line_buffering=False, write_through=False):
if newline is not None and not isinstance(newline, str):