Das deutsche Python-Forum

http://docs.python.org/library/doctest.html#how-are-docstring-examples-recognized hat geschrieben: If you continue a line via backslashing in an interactive session, or for any other reason use a backslash, you should use a raw docstring, which will preserve your backslashes exactly as you type them […] Otherwise, the backslash will be interpreted as part of the string. For example, the “\” above would be interpreted as a newline character. Alternatively, you can double each backslash in the doctest version (and not use a raw string)