code: function(intersection, size) {
      var i, j, ret;
      if (intersection.charCodeAt(1) > CODE_9) { // "aa"
  	i = intersection.charCodeAt(0) - CODE_a + 1;
  	j = intersection.charCodeAt(1) - CODE_a + 1;
  	ret = horizontal(i, "A1") + vertical(j, "A1", size);
      }
      else { // "A1"
  	i = intersection.charCodeAt(0) - CODE_A + 1;
  	var skipI = i >= 9 ? 1 : 0;
  	i -= skipI;
  	j = size - (+intersection.substring(1)) + 1;
  	ret = horizontal(i, "aa") + vertical(j, "aa", size);
      }
      return ret;
  }
docs: Translates intersection in other coordinate system.
  
  @param {string} intersection either in "A1" or "aa" coordinates
  @param {number} size the grid base (9, 13, 19)
  @returns {string}