sub _predecode {
    my $enc;
    if    ( $_[0] =~ /^\xEF\xBB\xBF/ ) { $enc = 'UTF-8';    }
    elsif ( $_[0] =~ /^\xFF\xFE/     ) { $enc = 'UTF-16le'; }
    elsif ( $_[0] =~ /^\xFE\xFF/     ) { $enc = 'UTF-16be'; }
    elsif (substr($_[0], 0, 100) =~ /^[^>]* encoding="([^"]+)"/) { $enc = $1; }
    else                               { $enc = 'UTF-8';    }
    return decode($enc, $_[0], Encode::FB_CROAK | Encode::LEAVE_SRC);
}