title: how to write value of multi-dimensional array to a text file
body: <p>let say I have this array</p>
  
  <pre><code>[0,0] = A
  [0,1] = B
  [0,2] = C
  [1,0] = D
  [1,1] = E
  [1,2] = F
  [2,0] = G
  [2,1] = H
  [2,2] = I
  [3,0] = J
  [3,1] = K
  [3,2] = L
  </code></pre>
  
  <p>I want them to be written on a text file like this:</p>
  
  <pre><code>A B C
  D E F
  G H I
  J K L
  </code></pre>
  
  <p>what am I supposed to do?</p>