make variable inventory slots

src/artifacts.rs

@@ -72,15 +72,21 @@ impl Potion {
             was_collected: false,
         }
     }
+
+    pub fn get_health(&self) -> usize {
+        self.health
+    }
 }
 
 impl Artifact for Potion {
     fn get_representation(&self) -> (&str, Color) {
         ("P", Color::Green)
     }
+
     fn get_immutable_position(&self) -> &Position {
         &self.position
     }
+
     fn collect(&mut self, player: &mut Player, messages: &mut Vec<String>) {
         // only consume potion of the player can gain at least one health point
         if !player.is_healthy() {
@@ -105,8 +111,3 @@ impl Artifact for Potion {
         self.was_collected
     }
 }
-impl Potion {
-    pub fn get_health(&self) -> usize {
-        self.health
-    }
-}