1 files changed, 4 insertions, 0 deletions
diff --git a/src/item.h b/src/item.h
index 84f062ab..9221098e 100644
--- a/src/item.h
+++ b/src/item.h
@@ -199,6 +199,10 @@ public:
     return _state;
   }
 
+  virtual string hash(string _nonce) const {
+    return "";
+  }
+
   virtual void define(const symbol_t::kind_t, const string&,
                       expr_t::ptr_op_t);
   virtual expr_t::ptr_op_t lookup(const symbol_t::kind_t kind,