code: def decode_csr(b64der):
      
      try:
          return x509.load_der_x509_csr(
              decode_b64jose(b64der), default_backend())
      except ValueError as error:
          raise DeserializationError(error)
docs: Decode JOSE Base-64 DER-encoded CSR.
  
      :param str b64der: The encoded CSR.
  
      :rtype: `cryptography.x509.CertificateSigningRequest`
      :return: The decoded CSR.