Escape from a iterate loop (ATL helpers)

Question

Is there a way to escape an iterate loop in helper like break in Java , in my example :

helper context activity!Activity def : print(s : String,s1:OrderedSet(String)) : String = 
s1->iterate(a; acc1 : String = '' | acc1+                                                                            
            if  ((a.target.name = b.target.name)and (a.source <> b.source))then
                        'print'
                     --break                                                        
        else '' 
        endif
        );