exact_equality(a,b){
return (a==b)
}
exact_inequality(a,b){
return !(a==b)
equality(a,b){
return (a=b)
inequality(a,b){
return !(a=b)
ordered_before(a,b){
return ("" a < "" b)
ordered_after(a,b){
return ("" a > "" b)