the classification functions.

=over 4

=item status_message( $code )

The status_message() function will translate status codes to human
readable strings. The string is the same as found in the constant
names above.  If the $code is unknown, then C<undef> is returned.

=item is_info( $code )

Return TRUE if C<$code> is an I<Informational> status code (1xx).  This
class of status code indicates a provisional response which can't have
any content.

=item is_success( $code )

Return TRUE if C<$code> is a I<Successful> status code (2xx).

=item is_redirect( $code )

Return TRUE if C<$code> is a I<Redirection> status code (3xx). This class of
status code indicates that further action needs to be taken by the
user agent in order to fulfill the request.

=item is_error( $code )

Return TRUE if C<$code> is an I<Error> status code (4xx or 5xx).  The function
return TRUE for both client error or a server error status codes.

=item is_client_error( $code )

Return TRUE if C<$code> is an I<Client Error> status code (4xx). This class
of status code is intended for cases in which the client seems to have
erred.

This function is B<not> exported by default.

=item is_server_error( $code )

Return TRUE if C<$code> is an I<Server Error> status code (5xx). This class
of status codes is intended for cases in which the server is aware
that it has erred or is incapable of performing the request.

This function is B<not> exported by default.

=back

=head1 BUGS

For legacy reasons all the C<HTTP_> constants are exported by default
with the prefix C<RC_>.  It's recommended to use explict imports and
the C<:constants> tag instead of relying on this.