Cannot Import Sensor from Carla

The error is as follows:
```
(carlarl) alex@fst-computer:~/Documents/222/Motion-Planning-on-CARLA$ python module_7.py 
Traceback (most recent call last):
  File "module_7.py", line 35, in <module>
    from carla            import sensor
ImportError: cannot import name 'sensor' from 'carla' (/home/alex/anaconda3/envs/carlarl/lib/python3.7/site-packages/carla/__init__.py)
```
