fixup! docs: test code snipets, generate output for surface_flows, fix

 hydro-project#814

hydroflow/examples/example_surface_flows_3_ports.rs

@@ -9,8 +9,7 @@ pub fn main() {
     };
     println!(
         "{}",
-        flow
-            .meta_graph()
+        flow.meta_graph()
             .expect("No graph found, maybe failed to parse.")
             .to_mermaid(&Default::default())
     );