code: def _whatsnd(data):
      
      hdr = data[:512]
      fakefile = BytesIO(hdr)
      for testfn in sndhdr.tests:
          res = testfn(hdr, fakefile)
          if res is not None:
              return _sndhdr_MIMEmap.get(res[0])
      return None
docs: Try to identify a sound file type.
  
      sndhdr.what() has a pretty cruddy interface, unfortunately.  This is why
      we re-do it here.  It would be easier to reverse engineer the Unix 'file'
      command and use the standard 'magic' file, as shipped with a modern Unix.