code: function(items) {
              if(!items)
                  return;
  
              var positions;
              if(this.settings.orientation == 'horizontal')
                  positions = ['top', 'bottom'];
              else
                  positions = ['left', 'right'];
  
              for(var i = 0; i < this.content.length; i++) {
                  if(this.content[i].forcePosition && positions.indexOf(this.content[i].forcePosition) >= 0) {
                          this.content[i].position = this.content[i].forcePosition;
                  } else if(!this.content[i].position) {
                      switch(this.content[i].type) {
                          case 'milestone':
                              if(this.settings.orientation == 'horizontal')
                                  this.content[i].position = 'top';
                              else
                                  this.content[i].position = 'right';
                              break;
                          case 'smallItem':
                              if(i == 0)
                                  this.content[i].position = this.settings.orientation == 'horizontal' ? 'top' : 'left';
                              else if(this.settings.orientation == 'horizontal' && this.content[i - 1].position == 'top')
                                  this.content[i].position = 'bottom';
                              else if(this.settings.orientation == 'horizontal' && this.content[i - 1].position == 'bottom')
                                  this.content[i].position = 'top';
                              else if(this.settings.orientation != 'horizontal' && this.content[i - 1].position == 'left')
                                  this.content[i].position = 'right';
                              else if(this.settings.orientation != 'horizontal' && this.content[i - 1].position == 'right')
                                  this.content[i].position = 'left';
                              else
                                  this.content[i].position = this.settings.orientation == 'horizontal' ? 'top' : 'left';
                              break;
                          case 'bigItem':
                              break;
                      }
                  }
              }
  
              return items;
          }
docs: Method that fill 'position' field, depending on item's forcePosition option, on item's type and on position of the previous item