code: def get_file_format(self):
          
          # Have cached file format?
          if self._file_fmt is not None:
              return self._file_fmt
  
          # Make the call to retrieve it.
          desc = AudioStreamBasicDescription()
          size = ctypes.c_int(ctypes.sizeof(desc))
          check(_coreaudio.ExtAudioFileGetProperty(
              self._obj, PROP_FILE_DATA_FORMAT, ctypes.byref(size),
              ctypes.byref(desc)
          ))
  
          # Cache result.
          self._file_fmt = desc
          return desc
docs: Get the file format description. This describes the type of
          data stored on disk.