Tab key doesn't work when typing in a class.

So you all would know how we press tab to get our cursor in front of a bracket after typing a code in the bracket right.
That is not working for me when I am writing a code in a class, specifically when I am defining a function.
Here, when my cursor is in the bracket, when I press tab, it just enter 4 spaces instead of moving the cursor.
This is really reducing my speed, I would really appreciate some help!

def __init__(self, name):
    --------