def eth_getStorageAt(self, address, position=0, block=BLOCK_TAG_LATEST):
        """https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_getstorageat

        :param address: Storage address
        :type address: str

        :param position: Position in storage (optional)
        :type position: int

        :param block: Block tag or number (optional)
        :type block: int or BLOCK_TAGS

        :rtype: int
        """
        block = validate_block(block)
        return hex_to_dec((yield from self.rpc_call('eth_getStorageAt',
                                                    [address,
                                                     hex(position),
                                                     block])))
https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_getstorageat

        :param address: Storage address
        :type address: str

        :param position: Position in storage (optional)
        :type position: int

        :param block: Block tag or number (optional)
        :type block: int or BLOCK_TAGS

        :rtype: int