unused local variable acrobot
diff --git a/gym/envs/classic_control/acrobot.py b/gym/envs/classic_control/acrobot.py
index 44d2a09988b..077b2b0622f 100644
--- a/gym/envs/classic_control/acrobot.py
+++ b/gym/envs/classic_control/acrobot.py
@@ -283,7 +283,7 @@ def derivs(x,t):
         yout = np.zeros((len(t), Ny), np.float_)
 
     yout[0] = y0
-    i = 0
+
 
     for i in np.arange(len(t) - 1):
 

remove redundant local variable