#27331: add policy keyword argument to all MIME subclasses.

Patch by Berker Peksag.
diff --git a/Lib/email/mime/audio.py b/Lib/email/mime/audio.py
index fbc1189..4bcd7b2 100644
--- a/Lib/email/mime/audio.py
+++ b/Lib/email/mime/audio.py
@@ -43,7 +43,7 @@
     """Class for generating audio/* MIME documents."""
 
     def __init__(self, _audiodata, _subtype=None,
-                 _encoder=encoders.encode_base64, **_params):
+                 _encoder=encoders.encode_base64, *, policy=None, **_params):
         """Create an audio/* type MIME document.
 
         _audiodata is a string containing the raw audio data.  If this data
@@ -68,6 +68,7 @@
             _subtype = _whatsnd(_audiodata)
         if _subtype is None:
             raise TypeError('Could not find audio MIME subtype')
-        MIMENonMultipart.__init__(self, 'audio', _subtype, **_params)
+        MIMENonMultipart.__init__(self, 'audio', _subtype, policy=policy,
+                                  **_params)
         self.set_payload(_audiodata)
         _encoder(self)