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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 get_tokens_list(self, registry_address: PaymentNetworkID):
 """Returns a list of tokens the node knows about"""

        tokens_list = views.get_token_identifiers(
            chain_state=views.state_from_raiden(self.raiden),
            payment_network_id=registry_address,
        )
        return tokens_list