union method
inherited
Creates a new set which contains all the elements of this set and other.
That is, the returned set contains all the elements of this Set and
all the elements of other.
final characters1 = <String>{'A', 'B', 'C'};
final characters2 = <String>{'A', 'E', 'F'};
final unionSet1 = characters1.union(characters2);
print(unionSet1); // {A, B, C, E, F}
final unionSet2 = characters2.union(characters1);
print(unionSet2); // {A, E, F, B, C}
Implementation
Set<String> union(Set<String> other) => readClasses().union(other);