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　　//given some amount of an asset and pair reserves,returns an equivalent amount of the other asset

　　//添加流动性的时候，通过该方法查询输入A的数量，需要多少个B

　　function quote(uint amountA,uint reserveA,uint reserveB)internal pure returns(uint amountB){

　　//判断数量，首次添加流动性，随意定价，不需要查询该方法

　　require(amountA>0,'UniswapV2Library:INSUFFICIENT_AMOUNT');

　　require(reserveA>0&&reserveB>0,'UniswapV2Library:INSUFFICIENT_LIQUIDITY');

　　//B数量=预期输入A的数量*B的储备量/A的储备量；//实际公式就是A/B=reserveA/reserveB,两个币的数量比例一致

　　amountB=amountA.mul(reserveB)/reserveA;

　　}

　　//given an input amount of an asset and pair reserves,returns the maximum output amount of the other asset

　　//通过精确输入金额,输入币的储备量，输出币的储备量，计算输出币的最大输出量

　　function getAmountOut(uint amountIn,uint reserveIn,uint reserveOut)internal pure returns(uint amountOut){

　　require(amountIn>0,'UniswapV2Library:INSUFFICIENT_INPUT_AMOUNT');

　　require(reserveIn>0&&reserveOut>0,'UniswapV2Library:INSUFFICIENT_LIQUIDITY');

　　//具体看下面的公式推导，要看该公式，首先要理解uniswap AMM,X*Y=K

　　uint amountInWithFee=amountIn.mul(997);//手续费都是扣输入额的千三，所以需要去掉千三后才是实际用于交易的金额

　　uint numerator=amountInWithFee.mul(reserveOut);//套下面公式理解吧！！

　　uint denominator=reserveIn.mul(1000).add(amountInWithFee);

　　amountOut=numerator/denominator;