title: Julia: Flattening array of array/tuples
body: <p>In Julia <code>vec</code> reshapes multidimensional arrays into one-dimension arrays.
  However it doesn't work for arrays of arrays or arrays of tuples.
  A part from using array comprehension, is there another way to flatten arrays of arrays/tuples? Or arrays of arrays/tuples of arrays/tuples? Or ...</p>