no way to compare when less than two revisions

Differences

This shows you the differences between two versions of the page.

@@ Line 1: / Line 1: @@
+<code python>
+>>> a
+Traceback (most recent call last):
+  File "<stdin>", line 1, in <module>
+NameError: name 'a' is not defined
+</code>
+<code python>
+>>> try:
+...   a
+... except:
+...   print("'a' is not defined.")
+...
+'a' is not defined.
+</code>