code: def get_ecdh_key(self, other):
          '''
          other-->Key25519 instance
          '''
          if self.__secretkey is None:
              raise KeyTypeError('Wrong key type for operation')
          # Copy because curve25519_dh_CreateSharedKey changes secretkey
          tmp_secretkey = ffi.new(C_SECRETKEY, self.secretkey)
          ecdh_key = ffi.new(C_SHAREDKEY)
          lib.curve25519_dh_CreateSharedKey(
              ecdh_key, other.pubkey, tmp_secretkey)
          del tmp_secretkey
          return ffi.get_bytes(ecdh_keyf get_ecdh_key(self, other):
          '''
          other-->Key25519 instance
          '''
          if self.__secretkey is None:
              raise KeyTypeError('Wrong key type for operation')
          # Copy because curve25519_dh_CreateSharedKey changes secretkey
          tmp_secretkey = ffi.new(C_SECRETKEY, self.secretkey)
          ecdh_key = ffi.new(C_SHAREDKEY)
          lib.curve25519_dh_CreateSharedKey(
              ecdh_key, other.pubkey, tmp_secretkey)
          del tmp_secretkey
          return ffi.get_bytes(ecdh_key)
docs: other-->Key25519 instance