\begin{methoddesc}[Message]{get_content_charset}{\optional{failobj}}
Return the \code{charset} parameter of the \mailheader{Content-Type}
-header. If there is no \mailheader{Content-Type} header, or if that
-header has no \code{charset} parameter, \var{failobj} is returned.
+header, coerced to lower case. If there is no
+\mailheader{Content-Type} header, or if that header has no
+\code{charset} parameter, \var{failobj} is returned.
Note that this method differs from \method{get_charset()} which
returns the \class{Charset} instance for the default encoding of the