feat: Adding toggle (#8)

* feat: Adding toggle

* Update src/lib.rs

Return unneded

Co-authored-by: EdJoPaTo <github@edjopato.de>

Co-authored-by: EdJoPaTo <github@edjopato.de>

src/lib.rs

@@ -58,6 +58,16 @@ impl TreeState {
         self.opened.remove(identifier)
     }
 
+    /// Toggles a tree node.
+    /// If the node is in opened then it calls `close()`. Otherwise it calls `open()`.
+    pub fn toggle(&mut self) {
+        if self.opened.contains(&self.selected()) {
+            self.close(&self.selected());
+        } else {
+            self.open(self.selected());
+        }
+    }
+
     pub fn close_all(&mut self) {
         self.opened.clear();
     }