warn "## heuristic date time: $1T$2\n" if $debug;
$worksheet->write_date_time( $row, $col, "$1T$2", $date_format );
} else {
+ $data = "'" . $data if $data =~ m/^=/; # escape data which looks like formula
$worksheet->write($row, $col, _c( $data ) );
}
}