x=>x;
x=>x*x;
x=>{x*x};
x=>{x*x;};
()=>1;
(x)=>x;
(x)=>x*x;
(x)=>{x*x};
(x)=>{x*x;};

x=>{x*=x;x};

(x)=>{x*=x;x};

[].sort((a,b)=>a-b);
[].sort((a,b)=>foo(a,b));
[].reduce((sum,{a,b})=>sum+=a+b,0);

setTimeout(()=>{1;2;3});

foo((a=1,...rest)=>rest[a]);

foo((a=1,b)=>b);

foo((a=1,b,)=>b);

async x=>x
async(x)=>x
async(x)=>{x}