Handles a `TokenNetworkCreated` event.

def handle_tokennetwork_new(raiden: 'RaidenService', event: Event):
    """ Handles a `TokenNetworkCreated` event. """
    data = event.event_data
    args = data['args']
    block_number = data['block_number']
    token_network_address = args['token_network_address']
    token_address = typing.TokenAddress(args['token_address'])
    block_hash = data['block_hash']

    token_network_proxy = raiden.chain.token_network(token_network_address)
    raiden.blockchain_events.add_token_network_listener(
        token_network_proxy=token_network_proxy,
        contract_manager=raiden.contract_manager,
        from_block=block_number,
    )

    token_network_state = TokenNetworkState(
        token_network_address,
        token_address,
    )

    transaction_hash = event.event_data['transaction_hash']

    new_token_network = ContractReceiveNewTokenNetwork(
        transaction_hash=transaction_hash,
        payment_network_identifier=event.originating_contract,
        token_network=token_network_state,
        block_number=block_number,
        block_hash=block_hash,
    )
    raiden.handle_and_track_state_change(new_token_network)