"o" here is a function that show the type of output [o←⎕fmt];
If i have one array a,
a←,¨ 1 2 3
o a
┌3─────────────┐
│┌1─┐ ┌1─┐ ┌1─┐│
││ 1│ │ 2│ │ 3││
│└~─┘ └~─┘ └~─┘2
└∊─────────────┘
and i have the element b
b←1
o b
1
~
i shouold build one array that show to be as
o ,¨ 1 1 2 3
┌4──────────────────┐
│┌1─┐ ┌1─┐ ┌1─┐ ┌1─┐│
││ 1│ │ 1│ │ 2│ │ 3││
│└~─┘ └~─┘ └~─┘ └~─┘2
└∊──────────────────┘
these below did not show the right list
o b,a
┌4───────────────┐
│ ┌1─┐ ┌1─┐ ┌1─┐│
│1 │ 1│ │ 2│ │ 3││
│~ └~─┘ └~─┘ └~─┘2