From a7fed6466bf63ef890ffc7d223144f05395ad08f Mon Sep 17 00:00:00 2001
From: Angus Griffith <16sn6uv@gmail.com>
Date: Tue, 16 Feb 2016 18:15:39 +0100
Subject: [PATCH] fix ParametricPlot bug

---
 mathics/builtin/plot.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mathics/builtin/plot.py b/mathics/builtin/plot.py
index 17ee972302..9308a81d11 100644
--- a/mathics/builtin/plot.py
+++ b/mathics/builtin/plot.py
@@ -91,10 +91,10 @@ def quiet_evaluate(expr, vars, evaluation, expect_list=False):
     value = dynamic_scoping(quiet_expr.evaluate, vars, evaluation)
     if expect_list:
         if value.has_form('List', None):
-            value = (extract_pyreal(item) for item in value.leaves)
+            value = [extract_pyreal(item) for item in value.leaves]
             if any(item is None for item in value):
                 return None
-            return list(value)  # force generator evaluation
+            return value
         else:
             return None
     else: