kn/;jn
function join(a,b){
var conc ="";
if(!a){
conc = " ";
}else if(!b){
for(var i=0; i < a.length;i++){
conc+=a[i]+" ";
}
}else{
for(var i=0; i < a.length;i++){
conc+=a[i]+b;
}
}
conc=conc.substring(0,conc.length-2)
return conc;
}