function _buys(uint256 id, uint256 amount) internal returns (bool) {
    require(buyEnabled); // @audit-info Buys can not be disabled if offer matching is disabled - this require statement should be moved to `buy` function
    if (amount == offers[id].pay_amt) {
        if (isOfferSorted(id)) {
            //offers[id] must be removed from sorted list because all of it is bought
            _unsort(id);
        } else {
            _hide(id);
        }
    }

    require(super.buy(id, amount));

    // If offer has become dust during buy, we cancel it
    if (
        isActive(id) &&
        offers[id].pay_amt < _dust[address(offers[id].pay_gem)]
    ) {
        dustId = id; //enable current msg.sender to call cancel(id)
        cancel(id);
    }
    return true;
}
