sends prekeys
        :return:
        :rtype:

def flush_keys(self, signed_prekey, prekeys, reboot_connection=False):
        """
        sends prekeys
        :return:
        :rtype:
        """
        preKeysDict = {}
        for prekey in prekeys:
            keyPair = prekey.getKeyPair()
            preKeysDict[self.adjustId(prekey.getId())] = self.adjustArray(keyPair.getPublicKey().serialize()[1:])

        signedKeyTuple = (self.adjustId(signed_prekey.getId()),
                          self.adjustArray(signed_prekey.getKeyPair().getPublicKey().serialize()[1:]),
                          self.adjustArray(signed_prekey.getSignature()))

        setKeysIq = SetKeysIqProtocolEntity(
            self.adjustArray(
                self.manager.identity.getPublicKey().serialize()[1:]
            ),
            signedKeyTuple,
            preKeysDict,
            Curve.DJB_TYPE,
            self.adjustId(self.manager.registration_id)
        )

        onResult = lambda _, __: self.on_keys_flushed(prekeys, reboot_connection=reboot_connection)
        self._sendIq(setKeysIq, onResult, self.onSentKeysError)