fn is a ConditionFn or ConditionFnLike string _ is underscore
option.fn = (index: string, value: string, _?) => parseInt(value) > 1; option.fn = "value > 1";
next should be MiddlewareConfig or "Gather"/"Noop"
type of Condition filter ( whitelisted / blacklisted ). The default is whitelist. type参数指定该Condition过滤器是白名单过滤还是黑名单, 默认是白名单
fn is a ConditionFn or ConditionFnLike string _ is underscore
option.fn = (index: string, value: string, _?) => parseInt(value) > 1; option.fn = "value > 1";