sub make_csv_format {
  my $me      = shift;
  my $color   = shift                 if @_;

  my $quote_item = sub {
    # ...
    # Remove ugly kludge with prefixed color information:
    $item =~ s/^#[\dA-F]{6}//i        unless $color;
    # ...
  }; # <------ This is line with warning.
  my $quote_row  = sub {
    my $items = shift;
    return join(",", map { $quote_item->($_) } @$items) . "\n";
  };

  # ...
}