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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 validate_addr(self, address, id=None, endpoint=None):
 """ returns whether or not addr string is valid Args: address: (str) address to lookup ( in format 'AXjaFSP23Jkbe6Pk9pPGT6NBDs1HVdqaXK') id: (int, optional) id to use for response tracking endpoint: (RPCEndpoint, optional) endpoint to specify to use Returns: json object of the result or the error encountered in the RPC call """

        return self._call_endpoint(VALIDATE_ADDR, params=[address], id=id, endpoint=endpoint)