public static HashSet <T> Union <T>(this HashSet <T> a, HashSet <T> b)
{
return(HashSetExtras <T> .Union(a, b));
}
public static HashSet <T> Intersection <T>(this HashSet <T> a, HashSet <T> b)
{
return(HashSetExtras <T> .Intersection(a, b));
}
public static HashSet <T> Difference <T>(this HashSet <T> a, HashSet <T> b)
{
return(HashSetExtras <T> .Difference(a, b));
}