I am running "echo1.py" in python 3.7.4 and rx 3.0 but i'm getting this error -->>AttributeError: type object 'Observable' has no attribute 'from_'

[ajaygbl]

HI sir,this is the error i am getting. thanks in advance for any help.

Traceback (most recent call last):
File "echo1.py", line 4, in
argv = Observable.from_(sys.argv[1:])
AttributeError: type object 'Observable' has no attribute 'from_'