code: def load_key(self, key):
          
          self._serialize(key)
          if isinstance(key, ec.EllipticCurvePrivateKey):
              self.priv_key = key
              self.pub_key = key.public_key()
          else:
              self.pub_key = key
  
          return self
docs: Load an Elliptic curve key
  
          :param key: An elliptic curve key instance, private or public.
          :return: Reference to this instance