In the Tcl::pTk module there is the following subroutine

# subroutine findINC copied from perlTk/Tk.pm
sub findINC {
    my $file = join('/',@_);                 # Normal location
    my $fileImage = join('/', $_[0], 'images', $_[1]); # alternate loc
+ation in the 'images' directory
    my $dir;
    $file  =~ s,::,/,g;
    $fileImage  =~ s,::,/,g;
    foreach $dir (@INC) {
    my $path;

        # check for normal location and 'images' location of the file
    return $path if (-e ($path = "$dir/$file") );
    return $path if (-e ($path = "$dir/$fileImage") );

    }
    return undef;
}
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So not weite sure about the object Tk->findINC