Add values, complete the board edges and nodes wise

src/lib.rs

@@ -14,7 +14,7 @@ pub struct Node {
 #[derive(Serialize, Deserialize, Debug, Default)]
 #[serde(default)]
 pub struct Board {
-    pub labels: HashMap<String, Vec<String>>,
+    pub labels: HashMap<String, HashSet<String>>,
     pub nodes: HashMap<usize, Node>,
 }
 impl Board {