go =>
   L1 = {1,2,3,4,5}, % define an array with {}
   L2 = {6,7,8,9},

   % The built-in array/list concatenation
   println(L1 ++ L2),

   % Using the built-in append/3 works only on lists
   % so the arrays must be converted to lists.
   append(L1.to_list,L2.to_list,L3),
   println(L3.to_array),
   nl.