uint startTime = block.timestamp + vestingTime - (totalCoins / coinsPerSecond);
uint coinsPerSecond = (totalCoins * (uint(100) - tree.pctUpFront)) / (vestingTime * 100);
// 10_000e6 * (100 - 99) / (365 * 86400 * 100)
// = 0
uint coinsPerSecond = (totalCoins * (uint(100) - tree.pctUpFront)) / (vestingTime * 100);
// 100_000e2 * 100 / (180 * 86400 * 100)
// = 0

uint coinsPerSecond = (totalCoins * (uint(100) - tree.pctUpFront)) * PRECISION / (vestingTime * 100);


currentWithdrawal = (block.timestamp - tranche.lastWithdrawalTime) * tranche.coinsPerSecond / PRECISION;
