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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_passphrase(self, prompt='Passphrase:'):
 """Ask the user for 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