Make verbose an argument for the fit function

examples/nba-history.rs

@@ -69,7 +69,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         model.observe(&[&winner], &[&loser], t);
     }
 
-    model.fit();
+    model.fit(true);
 
     println!("Probability that CHI beats BOS...");