diff --git a/examples/point_maze_td3.py b/examples/point_maze_td3.py
index a31326271..e72351839 100644
--- a/examples/point_maze_td3.py
+++ b/examples/point_maze_td3.py
@@ -9,13 +9,12 @@
 from tianshou.trainer import offpolicy_trainer
 from tianshou.data import Collector, ReplayBuffer
 from tianshou.env import VectorEnv, SubprocVectorEnv
-
 from continuous_net import Actor, Critic
 
 
 def get_args():
     parser = argparse.ArgumentParser()
-    parser.add_argument('--task', type=str, default='PointMaze-v0')
+    parser.add_argument('--task', type=str, default='PointMaze-v1')
     parser.add_argument('--seed', type=int, default=1626)
     parser.add_argument('--buffer-size', type=int, default=20000)
     parser.add_argument('--actor-lr', type=float, default=3e-5)
diff --git a/tianshou/env/__init__.py b/tianshou/env/__init__.py
index 81f20145b..878c800b5 100644
--- a/tianshou/env/__init__.py
+++ b/tianshou/env/__init__.py
@@ -2,8 +2,10 @@
 from tianshou.env.common import EnvWrapper, FrameStack
 from tianshou.env.vecenv import BaseVectorEnv, VectorEnv, \
     SubprocVectorEnv, RayVectorEnv
+from tianshou.env import mujoco
 
 __all__ = [
+    'mujoco',
     'EnvWrapper',
     'FrameStack',
     'BaseVectorEnv',
diff --git a/tianshou/env/mujoco/point_maze_env.py b/tianshou/env/mujoco/point_maze_env.py
index 81ce29dc0..c8e8ef84b 100644
--- a/tianshou/env/mujoco/point_maze_env.py
+++ b/tianshou/env/mujoco/point_maze_env.py
@@ -233,7 +233,7 @@ def get_top_down_view(self):
 
         def valid(row, col):
             return self._view.shape[0] > row >= 0 \
-                and self._view.shape[1] > col >= 0
+                   and self._view.shape[1] > col >= 0
 
         def update_view(x, y, d, row=None, col=None):
             if row is None or col is None:
@@ -252,36 +252,36 @@ def update_view(x, y, d, row=None, col=None):
 
             if valid(row, col):
                 self._view[row, col, d] += (
-                    (min(1., row_frac + 0.5) - max(0., row_frac - 0.5)) *
-                    (min(1., col_frac + 0.5) - max(0., col_frac - 0.5)))
+                        (min(1., row_frac + 0.5) - max(0., row_frac - 0.5)) *
+                        (min(1., col_frac + 0.5) - max(0., col_frac - 0.5)))
             if valid(row - 1, col):
                 self._view[row - 1, col, d] += (
-                    (max(0., 0.5 - row_frac)) *
-                    (min(1., col_frac + 0.5) - max(0., col_frac - 0.5)))
+                        (max(0., 0.5 - row_frac)) *
+                        (min(1., col_frac + 0.5) - max(0., col_frac - 0.5)))
             if valid(row + 1, col):
                 self._view[row + 1, col, d] += (
-                    (max(0., row_frac - 0.5)) *
-                    (min(1., col_frac + 0.5) - max(0., col_frac - 0.5)))
+                        (max(0., row_frac - 0.5)) *
+                        (min(1., col_frac + 0.5) - max(0., col_frac - 0.5)))
             if valid(row, col - 1):
                 self._view[row, col - 1, d] += (
-                    (min(1., row_frac + 0.5) - max(0., row_frac - 0.5)) *
-                    (max(0., 0.5 - col_frac)))
+                        (min(1., row_frac + 0.5) - max(0., row_frac - 0.5)) *
+                        (max(0., 0.5 - col_frac)))
             if valid(row, col + 1):
                 self._view[row, col + 1, d] += (
-                    (min(1., row_frac + 0.5) - max(0., row_frac - 0.5)) *
-                    (max(0., col_frac - 0.5)))
+                        (min(1., row_frac + 0.5) - max(0., row_frac - 0.5)) *
+                        (max(0., col_frac - 0.5)))
             if valid(row - 1, col - 1):
                 self._view[row - 1, col - 1, d] += (
-                    (max(0., 0.5 - row_frac)) * max(0., 0.5 - col_frac))
+                        (max(0., 0.5 - row_frac)) * max(0., 0.5 - col_frac))
             if valid(row - 1, col + 1):
                 self._view[row - 1, col + 1, d] += (
-                    (max(0., 0.5 - row_frac)) * max(0., col_frac - 0.5))
+                        (max(0., 0.5 - row_frac)) * max(0., col_frac - 0.5))
             if valid(row + 1, col + 1):
                 self._view[row + 1, col + 1, d] += (
-                    (max(0., row_frac - 0.5)) * max(0., col_frac - 0.5))
+                        (max(0., row_frac - 0.5)) * max(0., col_frac - 0.5))
             if valid(row + 1, col - 1):
                 self._view[row + 1, col - 1, d] += (
-                    (max(0., row_frac - 0.5)) * max(0., 0.5 - col_frac))
+                        (max(0., row_frac - 0.5)) * max(0., 0.5 - col_frac))
 
         # Draw ant.
         robot_x, robot_y = self.wrapped_env.get_body_com("torso")[:2]
@@ -376,7 +376,8 @@ def get_range_sensor_obs(self):
         sensor_readings = np.zeros((self._n_bins, 3))
         for ray_idx in range(self._n_bins):
             ray_ori = (ori - self._sensor_span * 0.5 + (
-                2 * ray_idx + 1.0) / (2 * self._n_bins) * self._sensor_span)
+                    2 * ray_idx + 1.0) /
+                       (2 * self._n_bins) * self._sensor_span)
             ray_segments = []
             # Get all segments that intersect with ray.
             for seg in segments:
@@ -401,8 +402,8 @@ def get_range_sensor_obs(self):
                        2 if maze_env_utils.can_move(seg_type) else  # Block.
                        None)
                 if first_seg["distance"] <= self._sensor_range:
-                    sensor_readings[ray_idx][idx] = (
-                        self._sensor_range - first_seg[
+                    sensor_readings[ray_idx][idx] = \
+                        (self._sensor_range - first_seg[
                             "distance"]) / self._sensor_range
         return sensor_readings