//runs first trial
 void OnEnable()
 {
     if (!(this.GetComponent <input_manager>().listening))
     {
         return;
     }
     if (!(input_manager.practice) || rg == null)
     {
         rg = new random_gen();
         t  = rg.gen_pos();
     }
     ij.Invoke(t.L, t.R);
 }
 public void ClearGens()
 {
     rg = null;
 }