[
    {
        "constant": true,
        "inputs": [
            {
                "internalType": "address",
                "name": "sourceTokenAddress",
                "type": "address"
            },
            {
                "internalType": "address",
                "name": "destTokenAddress",
                "type": "address"
            }
        ],
        "name": "queryRate",
        "outputs": [
            {
                "internalType": "uint256",
                "name": "rate",
                "type": "uint256"
            },
            {
                "internalType": "uint256",
                "name": "precision",
                "type": "uint256"
            }
        ],
        "payable": false,
        "stateMutability": "view",
        "type": "function"
    }
]