add TupleKey class

src/types/TupleKey.ts

@@ -0,0 +1,19 @@
+const separator = "|";
+
+export class TupleKey<T extends any[]> {
+  public readonly tuple: T;
+  private readonly strKey: string;
+
+  constructor(...tuple: T) {
+    this.tuple = tuple;
+    this.strKey = tuple.join(separator);
+  }
+
+  toString(): string {
+    return this.strKey;
+  }
+
+  valueOf(): string {
+    return this.strKey;
+  }
+}