Torch to pytorch: torch.class('foo') equivalent?

I am trying to transcribe some code from a Lua repo

local BetSizing = torch.class('BetSizing')

function BetSizing:__init(fractions)

I have been unable to find the equivalent implementation with python using pytorch. I need to know what I need to hand to the class definition as an argument so that it would mirror what’s going on in the Lua version

class BetSizing( $something goes in here$ ):
    def __init__(self):


Please see the documentation on how to create new Modules.