modes:pair: implement Display for Pair

src/modes/pair.rs

@@ -37,3 +37,12 @@ impl Pair {
         }
     }
 }
+
+use std::fmt::{Display, Formatter, Result};
+
+impl Display for Pair {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+        write!(f, "Pair({}, {})", self.0, self.1)
+    }
+}
+