Correct yaml bool syntax

homework4/src/main.rs

@@ -83,8 +83,8 @@ impl PowerSocket {
 
     fn get_string_state(&self) -> String {
         let s = match self.get_state() {
-            PowerState::Off => String::from("OFF"),
-            PowerState::On => String::from("ON"),
+            PowerState::Off => String::from("off"),
+            PowerState::On => String::from("on"),
         };
         s
     }