no _get_value in open object states

[yanan1116]

hi authors,

i find that there is no method _get_value in open https://github.com/StanfordVL/iGibson/blob/master/igibson/object_states/open.py
while in other states, i can find it, such as in https://github.com/StanfordVL/iGibson/blob/master/igibson/object_states/toggle.py#L23

therefore, each time when i try to set the value to be true for the open state,

import igibson.object_states as object_states
# igibson/object_states/object_state_base.py
 obj.states[object_states.Open].set_value(True)

obj.states[object_states.Open].get_value() is always False.

Any reason for this ?

thanks.