    function addGate(uint priceFloor, uint priceDecay, uint priceIncrease, uint priceIncreaseDenominator, address beneficiary) external {
        // prefix operator increments then evaluates
        Gate storage gate = gates[++numGates];
        gate.priceFloor = priceFloor;
        gate.decayFactor = priceDecay;
        gate.priceIncreaseFactor = priceIncrease;
        gate.priceIncreaseDenominator = priceIncreaseDenominator;
        gate.beneficiary = beneficiary;
    }
    function addGate(uint priceFloor, uint priceDecay, uint priceIncrease, uint priceIncreaseDenominator, address beneficiary) external {
        require(priceFloor != 0, "Price floor must be nonzero");
        require(priceIncreaseDenominator != 0, "Denominator must be nonzero");
        // prefix operator increments then evaluates
        Gate storage gate = gates[++numGates];
        gate.priceFloor = priceFloor;
        gate.decayFactor = priceDecay;
        gate.priceIncreaseFactor = priceIncrease;
        gate.priceIncreaseDenominator = priceIncreaseDenominator;
        gate.beneficiary = beneficiary;
    }
