returns the union of two sets
set3 = the_union(set1,set2)
set
The function the_union returns the set set3 obtained by forming the union of the sets set1 and set2.
the_union
set3
set1
set2
set1=define_set("a","c") set2=define_set("b","c","d") set3=the_union(set1,set2)