How to print 2d array

I want to print 2D array 

a!localVariables(
local!a:{{1,2}, {3,4},{6,7}},
a!forEach(
items: local!a,
expression: fv!item
))

This will give below result

1
2
3
4
6
7

But I want to print the result in below form

1,2
3,4
6,7

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