function triggerAirDrop(address recipient)
        public
        onlyOwner
    {
        numOfCitizensWhoReceivedDrops = numOfCitizensWhoReceivedDrops.add(1);

        require(
            numOfCitizensWhoReceivedDrops <= airdropReceiversLimit &&
            !claimedAirdropTokens[recipient],
            "Cannot give more tokens than airdropShare and cannot airdrop to an address that already receive tokens"
        );

        claimedAirdropTokens[recipient] = true;

        
        sendTokensToUser(recipient, tokenAmountPerUser);
        emit TokenDrop(recipient, tokenAmountPerUser);
    }