def METHOD_NAME() -> str:
    mainnet_node_url = os.environ.get("ETHEREUM_MAINNET_NODE")
    if hasattr(METHOD_NAME, "checked"):  # Just check node first time
        return mainnet_node_url
    if not mainnet_node_url:
        pytest.skip(
            "Mainnet node not defined, cannot test oracles", allow_module_level=True
        )
    else:
        try:
            response = requests.post(
                mainnet_node_url,
                timeout=5,
                json={
                    "jsonrpc": "2.0",
                    "method": "eth_blockNumber",
                    "params": [],
                    "id": 1,
                },
            )
            if not response.ok:
                pytest.fail(
                    f"Problem connecting to mainnet node {response.status_code} - {response.content}"
                )
        except IOError:
            pytest.fail("Problem connecting to the mainnet node")
    METHOD_NAME.checked = True
    return mainnet_node_url