diff --git a/advanced-iterators.html b/advanced-iterators.html
index d780ce6..242466e 100755
--- a/advanced-iterators.html
+++ b/advanced-iterators.html
@@ -544,6 +544,7 @@ for guess in itertools.permutations(digits, len(characters)):
File "<string>", line 1, in <module>
NameError: name 'x' is not defined
>>> eval("x * 5", {"x": x}, {}) ②
+25
>>> import math
>>> eval("math.sqrt(x)", {"x": x}, {}) ③
Traceback (most recent call last):