BEGIN { @AnyDBM_File::ISA = qw(DB_File GDBM_File NDBM_File) }
    use AnyDBM_File;

    use POSIX; use NDBM_File; use DB_File;
    tie %newhash,  'DB_File', $new_filename, O_CREAT|O_RDWR;
    tie %oldhash,  'NDBM_File', $old_filename, 1, 0;
    %newhash = %oldhash;