code: def encrypt(plaintext_str, keys):
      
      assert keys, 'Must provide at least one key to encrypt with'
      ctx = gpg.core.Context(armor=True)
      out = ctx.encrypt(plaintext_str, recipients=keys, sign=False,
                        always_trust=True)[0]
      return out
docs: Encrypt data and return the encrypted form.
  
      :param bytes plaintext_str: the mail to encrypt
      :param key: optionally, a list of keys to encrypt with
      :type key: list[gpg.gpgme.gpgme_key_t] or None
      :returns: encrypted mail
      :rtype: str