code: def sign_decorated(self, data):
          
          signature = self.sign(data)
          hint = self.signature_hint()
          return Xdr.types.DecoratedSignature(hint, signature)
docs: Sign a bytes-like object and return the decorated signature.
  
          Sign a bytes-like object by signing the data using the signing
          (private) key, and return a decorated signature, which includes the
          last four bytes of the public key as a signature hint to go along with
          the signature as an XDR DecoratedSignature object.
  
          :param bytes data: A sequence of bytes to sign, typically a
              transaction.