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    my ( $ref, $filename, $path )= @_;

    # return what we know of this module
    if ( !ref $ref ) {
        $ref =~ s#/#::#;
        return $IFDEF{$ref};
    }

    # check all directories and handlers
    foreach (@INC) {

        # let that INC handle do it if it is an INC handle and it's not us
        if (ref) {
            goto &$_ unless $_ eq $ref;
        }

        # we found the file
        elsif ( -f ( $path= "$_/$filename" ) ) {

            # create temp file
            open( my $in, $path ) or next;
            my $out= IO::File->new_tmpfile
              or die "Failed to create temporary file for '$path': $!\n";
            $filename =~ s#/#::#;
            $IFDEF{$filename}= $path;

            # process all lines
            local $_= \my $foo; # current state of localizing $_ ?
            while ( readline $in ) {
                &oneline;
                print $out $_;
            }
            close $in;
            &reset;

            # make sure we start reading from start again
            $out->seek( 0, 0 ) or die "Failed to seek: $!\n";

            return $out;
        }
    }

    # indicate that the rest should be searched (which will fail)
    return;
} );

# satisfy require
1;

#---------------------------------------------------------------------------
# process
#
# Process a string (consisting of many lines)
#
#  IN: 1 string to process
# OUT: 1 processed string (in place change if called in void context)

sub process {

    # process all lines
    my @line= split m#(?<=$/)#, $_[0];
    &reset;
    local $_= \my $foo;
    &oneline foreach @line;

    # close of activating section (e.g. when called by "load")
    push @line,"}$/" if $ACTIVATING;

    # return if not in void context
    return join( '', @line ) if defined wantarray;

    # change in place
    $_[0]= join( '',@line );

    return undef;
} #process

#---------------------------------------------------------------------------
# reset
#
# Reset all internal variables to a known state

sub reset { $ACTIVATING= $INPOD= $DEPTH= 0 } #reset

#---------------------------------------------------------------------------
# oneline
#
# Process one line in $_ in place

sub oneline {

    # let the world know if we should
    print STDERR "<$_" if DIFF;

    # it's a pod marker
    if ( m#^=(\w+)# ){

        # going back to source
        if ( $1 eq 'cut' ) {
            $_= $ACTIVATING ? "}$/" : $/;
            &reset;
        }

        # beginning potentially special pod section
        elsif ( $1 eq 'begin' ) {
            if ( m#^=begin\s+([A-Z_0-9]+)\b# ) {

                # activating
                if ( $ALL or $ENV{$1} ) {
                    $_= $ACTIVATING ? "}{$/" : "{;$/";
                    $ACTIVATING= 1;
                    $INPOD=      0;
                }

                # not activating now
                else {
                    $_= $ACTIVATING ? "}$/" : $/;
                    $ACTIVATING= 0;
                    $INPOD=      1;
                }
            }