code: function generateSequence(seq, check) {
    seq = seq.substr(0,12) + '' + check;
  
    var first = seq.substr(0,1),
      group1 = seq.substr(1,6),
      group2 = seq.substr(7);
  
    var left = [],
      right = [],
      enc = ENCODE_GROUPS[parseInt(first)],
      dInt;
  
    for (var i = 0; i < 6; i++) {
      dInt = parseInt(group1[i]);
      left = left.concat( BARMAP[ enc[i] ][ dInt ] );
    }
  
    for (var i = 0; i < 6; i++) {
      dInt = parseInt(group2[i])
      right = right.concat( BARMAP[RIGHT][ dInt ]   );
    }
  
    return [].concat(START, left, MIDDLE, right, END);
  }
docs: /*
  generate ean13 sequence
  
  @param String seq - sequence
  @param Int|String check - check digit
  @return Array<Number> - array of barwidth