diff --git a/more_math/helper_functions.py b/more_math/helper_functions.py
index 87827cb..8ecdafa 100644
--- a/more_math/helper_functions.py
+++ b/more_math/helper_functions.py
@@ -54,4 +54,5 @@ def comonLazy(expr, a, b=None, c=None, d=None, w=0.0, x=0.0, y=0.0, z=0.0):
         print("Variable is None:", variables.get(token.text) is None)
         if token.text in variables and variables[token.text] is None:
             need_eval.append(token.text)
-    print ("Need eval:", need_eval)
\ No newline at end of file
+    print ("Need eval:", need_eval)
+    return need_eval
\ No newline at end of file