From 4b92a387a9328a9072e9f48877c03ee9b714f81c Mon Sep 17 00:00:00 2001
From: samreid <reids@colorado.edu>
Date: Mon, 17 Aug 2020 18:14:09 -0600
Subject: [PATCH] Improve state scope check, see
 https://github.com/phetsims/tandem/issues/193

---
 js/Tandem.js | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/js/Tandem.js b/js/Tandem.js
index 0206b8a6..d22dabb4 100644
--- a/js/Tandem.js
+++ b/js/Tandem.js
@@ -164,6 +164,16 @@ class Tandem {
     }
   }
 
+  /**
+   * Returns true if this Tandem has the specified ancestor Tandem.
+   * @param ancestor
+   * @returns {boolean}
+   * @public
+   */
+  hasAncestor( ancestor ) {
+    return this.parentTandem === ancestor || ( this.parentTandem && this.parentTandem.hasAncestor( ancestor ) );
+  }
+
   /**
    * Removes a PhetioObject and signifies to listeners that it has been removed.
    * @param {PhetioObject} phetioObject