// PreConditions:
 // PostConditions: allows submersible object to change current 3D grid level to go up
 public void MoveDown(Submersible R1)
 {
     if (R1.IsPoweredup() && (R1.getCurrentLevel() != 10))
     {
         R1.setCurrentLevel(R1.getCurrentLevel() + 1);
     }
 }
 // PreConditions:
 // PostConditions: allows submersible object to change current 3D grid level to go down
 public void MoveUp(Submersible R1)
 {
     if (R1.IsPoweredup() && (R1.getCurrentLevel() != 0))
     {
         R1.setCurrentLevel(R1.getCurrentLevel() - 1);
     }
 }