Special syntax of the for loop

Hello to all,

this morning I discovered a new type of use of the for loop. My first exploration leads me to think that it is a possibility to enumerate a JSON structure (complex). The syntax is :
for id, [var of value] in [JSON] do

    // in this context, id is the key of the JSON and [var of value] contains the value of the key

end;

See this example to enumerate the content of the JSON variable config

var config := {
    sep: ",",
    qut: """",
    lf:"%0D%0A",
    numberFormat: "point",
    dateFormat: "locale",
    header: true,
    sepHeader: false,
    encoding: "utf8"
}

for id, value in config do
 id + " = " + value;
end;

return : 

sep = ,
qut = "
lf = %0D%0A
numberFormat = point
dateFormat = locale
header = true
sepHeader = false
encoding = utf8

I think there are many other possibilities, but I haven't found them yet. Maybe someone has another idea to use this type of for loop?