diff --git a/Palette/env/engine.py b/Palette/env/engine.py
index 8dcc260..eb3bb8b 100644
--- a/Palette/env/engine.py
+++ b/Palette/env/engine.py
@@ -29,7 +29,7 @@ class SeaEnvEngine(object):
         ship_radius: int,
         ship_velocity: int,
 
-        sonar_spread_times: int,    
+        sonar_spread_times: int,
 
         obstacles: dict,
 
@@ -129,7 +129,6 @@ class SeaEnvEngine(object):
             cur_obstacle = self.create_rectangle_obstacle(x, y, width, height)
             self.obstacles.append(cur_obstacle)
             self.obstacles_w_h.append((width, height))
-            # label the position of obstacles as -1
             for i in range(x//self.field_size[0], (x+width)//self.field_size[0]):
                 for j in range(y//self.field_size[1], (y+height)//self.field_size[1]):
                     self.fields[i, self.fields.shape[1]-j-1] = -1