code: def load_application_key_file(self, filename=b'spotify_appkey.key'):
          
          with open(filename, 'rb') as fh:
              self.app_key = fh.read()
docs: Load your libspotify application key file.
  
          If called without arguments, it tries to read ``spotify_appkey.key``
          from the current working directory.
  
          This is an alternative to setting :attr:`application_key` yourself. The
          file must be a binary key file, not the C code key file that can be
          compiled into an application.