From fe83f468f6b53c3223b2ab5ad7b49d5be51ac458 Mon Sep 17 00:00:00 2001
From: "Eric V. Smith" <eric@trueblade.com>
Date: Fri, 7 Aug 2015 22:25:27 -0400
Subject: [PATCH] Added another run time error example.

---
 pep-0498.txt | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/pep-0498.txt b/pep-0498.txt
index 60b8c3ec9..e217d0342 100644
--- a/pep-0498.txt
+++ b/pep-0498.txt
@@ -276,8 +276,8 @@ Invalid expressions::
   SyntaxError: invalid syntax
 
 Run time errors occur when evaluating the expressions inside an
-f-string. Note that an f-string can be executed multiple times, and
-work sometimes and raise an error other times::
+f-string. Note that an f-string can be evaluated multiple times, and
+work sometimes and raise an error at other times::
 
   >>> d = {0:10, 1:20}
   >>> for i in range(3):
@@ -289,6 +289,17 @@ work sometimes and raise an error other times::
     File "<stdin>", line 2, in <module>
   KeyError: 2
 
+or::
+
+  >>> for x in (32, 100, 'fifty'):
+  ...   f'x = {x:+3}'
+  ...
+  'x = +32'
+  'x = +100'
+  Traceback (most recent call last):
+    File "<stdin>", line 2, in <module>
+  ValueError: Sign not allowed in string format specifier
+
 Leading whitespace in expressions is skipped
 --------------------------------------------