Afterthought of Prometheus metrics for Warp
```rust use prometheus::Registry; use warp_prometheus::Metrics; use warp::Filter;
let registry: Registry = Registry::new();
let path_includes: Vec
let route_one = warp::path("hello") .and(warp::path::param()) .and(warp::header("user-agent")) .map(|param: String, agent: String| { format!("Hello {}, whose agent is {}", param, agent) });
let metrics = Metrics::new(®istry, &path_includes);
let test_routes = route_one.with(warp::log::custom(move |log| {
metrics.http_metrics(log)
}));
```