> L1 := [ 1, 2, 3 ];
                            L1 := [1, 2, 3]

> L2 := [ a, b, c ];
                            L2 := [a, b, c]

> [ op( L1 ), op( L2 ) ];
                           [1, 2, 3, a, b, c]

> [ L1[], L2[] ]; # equivalent, just different syntax
                           [1, 2, 3, a, b, c]