code: def ec_construct_private(num):
      
      pub_ecpn = ec.EllipticCurvePublicNumbers(num['x'], num['y'],
                                               NIST2SEC[as_unicode(num['crv'])]())
      priv_ecpn = ec.EllipticCurvePrivateNumbers(num['d'], pub_ecpn)
      return priv_ecpn.private_key(default_backend())
docs: Given a set of values on public and private attributes build a elliptic
      curve private key instance.
  
      :param num: A dictionary with public and private attributes and their values
      :return: A
          cryptography.hazmat.primitives.asymmetric.ec.EllipticCurvePrivateKey
          instance.