The"sharing"of the metauniverse ontology can be expressed in the form of standardization,which is the best order obtained by consensus within a certain range on the basis of scientific research and theoretical practice.The standards of the universe can be divided into five categories:basic,technology and platform

　　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');

　　uint amountInWithFee=amountIn.mul(997);

　　uint numerator=amountInWithFee.mul(reserveOut);

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

　　amountOut=numerator/denominator;

　　}
　　//给定资产的输出量和对准备金，返回其他资产所需的输入量

　　//(x+a)(y-b)=xy

　　//a=bx/(y-b)

　　//考虑手续费：

　　//实际a`=a*1000/997

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

　　require(amountOut>0,'UniswapV2Library:INSUFFICIENT_OUTPUT_AMOUNT');

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

　　uint numerator=reserveIn.mul(amountOut).mul(1000);

　　uint denominator=reserveOut.sub(amountOut).mul(997);

　　//加一是防止数据溢出

　　amountIn=(numerator/denominator).add(1);

　　}

　　function getAmountsOut(address factory,uint amountIn,address[]memory path)internal view returns(uint[]memory amounts){

　　require(path.length>=2,'UniswapV2Library:INVALID_PATH');

　　amounts=new uint[](path.length);

　　amounts[0]=amountIn;

　　for(uint i;i<path.length-1;i++){

　　(uint reserveIn,uint reserveOut)=getReserves(factory,path<i>,path[i+1]);

　　amounts[i+1]=getAmountOut(amounts<i>,reserveIn,reserveOut);

　　}

　　}

　　data and protocol,content and asset,application and service,governance and supervision.Basic standards establish a common language environment for other standards,including terms,ontology and classification,code and identification,reference architecture,etc.