code: def get_passphrase(self, prompt='Passphrase:'):
          
          passphrase = None
          if self.cached_passphrase_ack:
              passphrase = self.cached_passphrase_ack.get()
          if passphrase is None:
              passphrase = interact(
                  title='{} passphrase'.format(self.device_name),
                  prompt=prompt,
                  description=None,
                  binary=self.passphrase_entry_binary,
                  options=self.options_getter())
          if self.cached_passphrase_ack:
              self.cached_passphrase_ack.set(passphrase)
          return passphrase
docs: Ask the user for passphrase.