use WWW::Mechanize 1.54;
warn WWW::Mechanize->new->agent;
my $mech = WWW::Mechanize->new( agent => 'Windows IE 6');
warn $mech->agent;
$mech->agent_alias( 'Windows IE 6');
warn $mech->agent;
__END__
WWW-Mechanize/1.54 at - line 2.
Windows IE 6 at - line 4.
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1) at - line 6.