> s := "some string";
                           s := "some string"

> t := "some string";
                           t := "some string"

> evalb( s = t ); # they are equal
                                  true

> addressof( s ) = addressof( t ); # not just equal data, but the same address in memory
                        3078334210 = 3078334210

> u := t: # copy reference