count_only output flag accept no value

src/comparemode.rs

@@ -62,8 +62,7 @@ impl CompareMode {
                         println!("{}: {:?}", $msg, $ret.len());
                     }
                 } else {
-                    $ret.iter().for_each(|e| println!("{e}"));
-                    println!("{}: {:?}", $msg, $ret.len());
+                    println!("{}", $ret.len());
                 }
             };
         }

src/options.rs

@@ -29,7 +29,7 @@ pub enum Commands {
         #[arg(short, long)]
         selection: Option<String>,
         /// OPTIONAL: when using selection specify to return count only or not
-        #[arg(short)]
+        #[arg(short, default_value="false", num_args = 0..2)]
         count_only: Option<bool>,
     },
 }