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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fromWeb3(cls, web3, addr=None):
 """ Generate an ENS instance with web3 :param `web3.Web3` web3: to infer connection information :param hex-string addr: the address of the ENS registry on-chain. If not provided, ENS.py will default to the mainnet ENS registry address. """

        return cls(web3.manager.provider, addr=addr)