1. Missing instruction of getting the instance of the body in python 2. Cannot import name 'ChassisControl' from 'pymycobot'

[SJoJoK]

I can get the instance of left/right arm by

ml = Mercury("/dev/left_arm")
mr = Mercury("/dev/right_arm")

but how can i get the instance of the body so that I can rotate the neck?

>>> from pymycobot import ChassisControl
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'ChassisControl' from 'pymycobot' (/home/elephant/.local/lib/python3.8/site-packages/pymycobot/__init__.py)

the version of pymycobot is 3.5.0b15