code: public void setSlotSharingGroup(SlotSharingGroup grp) {
  		if (this.slotSharingGroup != null) {
  			this.slotSharingGroup.removeVertexFromGroup(id);
  		}
  
  		this.slotSharingGroup = grp;
  		if (grp != null) {
  			grp.addVertexToGroup(id);
  		}
  	}
docs: Associates this vertex with a slot sharing group for scheduling. Different vertices in the same
  slot sharing group can run one subtask each in the same slot.
  
  @param grp The slot sharing group to associate the vertex with.