        for (uint256 i = epochIndex; i < tokenEpochs; i++) {
            //only claimable after rewards are "locked in"
            if (rewardEpochs[_token][i] < latestEpoch) {
                claimableTokens += _claimableRewards(_account, _token, rewardEpochs[_token][i]);
                //return index user claims should be set to
                epochIndex = i + 1;
            }
        }
        uint256 latestEpoch = auraLocker.epochCount() - 1;
        // e.g. tokenEpochs = 31, 21
        uint256 tokenEpochs = rewardEpochs[_token].length;

        // e.g. epochIndex = 0
        uint256 epochIndex = userClaims[_token][_account];
        // e.g. epochIndex = 27 > 0 ? 27 : 0 = 27
        epochIndex = _startIndex > epochIndex ? _startIndex : epochIndex;
            while (epochs[epochs.length - 1].date != currentEpoch) {
                uint256 nextEpochDate = uint256(epochs[epochs.length - 1].date).add(rewardsDuration);
                epochs.push(Epoch({ supply: 0, date: uint32(nextEpochDate) }));
            }
