implement unique ID function

src/lib.rs

@@ -148,7 +148,17 @@ fn segments_from_string(string: String) -> Vec<String> {
 /// e.g. pass all tile IDs into this to get a new non-conflicting tile ID
 #[inline]
 fn new_unique_id(ids: Vec<String>) -> String {
-    "hello".to_string()
+    let mut new_id: u64 = 0;
+
+    for id in ids {
+        if new_id != from_base36(&id) {
+            break;
+        }
+
+        new_id += 1;
+    }
+
+    return to_base36(new_id);
 }
 
 pub trait Quote {