x =: 1, 2, 3, 4
   y =: 'a', 'b', 'c'
   \ create z as row with keys from -1 to 3
   z =: new row
   ?# i =: from -1 upto 3
       z[i] =: i+4

   ?# i =: tuple x give keys
     print i, x[i], y[i], z[i]
   print ''
   ?# i =: row z give keys
     print i, x[i], y[i], z[i]
   print ''
   ?# i =: from 0 upto 4
     print i, x[i], y[i], z[i]