static if(!(T1.length == 0 || T2.length == 0))
static if(!(is(T1[0]) && is(T2[0])))
static if(!is(T1[0]) && !is(T2[0]))
static if(is(typeof(T1[0]) == void) && is(typeof(T2[0]) == void))
static if(!(__traits(compiles, T1[0].opEquals!(T2[0]))))
static if(__traits(compiles, T2[0].opEquals!(T1[0])))