Marc-Andre Lemburg <mal@lemburg.com> noted that the encode() string method

was added in 2.0.

Doc/lib/libstdtypes.tex

@@ -425,6 +425,7 @@ error handling scheme.  The default for \var{errors} is
 \code{'strict'}, meaning that encoding errors raise a
 \exception{ValueError}.  Other possible values are \code{'ignore'} and
 \code{'replace'}.
+\versionadded{2.0}
 \end{methoddesc}
 
 \begin{methoddesc}[string]{endswith}{suffix\optional{, start\optional{, end}}}