code: function() {
  
              var step = this.step;
              var cost = this.cost();
  
              return [
                  { offsetX: step  , offsetY: 0     , cost: cost },
                  { offsetX: 0     , offsetY: step  , cost: cost },
                  { offsetX: -step , offsetY: 0     , cost: cost },
                  { offsetX: 0     , offsetY: -step , cost: cost }
              ];
          }
docs: an array of directions to find next points on the route different from start/end directions