sub read_spec($)
{
    my $filename = shift;
    local $/;
    open(my $fh, "<$filename") or die "Can't open filename";
    my $content = <$fh>;

    $content =~ s{\s+$}{}m;

    # ...
}

##</code><code>##

    $content =~ s{\s+$}{}m;
    $content =~ s{\t+$}{}m;

##</code><code>##

    $content =~ s{[ \t]+$}{}m;