# update sheet
sub update_sheet {
  my ($kw,$value,$comment) = @_;
  my ($sht,$r,$c) = @{$kwhashref->{$kw}}[0..2];
  my $sel = $Book->Worksheets($sht)->Cells($r,$c+1);
  $sel->Insert({ Shift => -4161}); # xlToRight
  $sel->{Value} = $value;
  $sel->AddComment( { Text=> $comment } );
  $kwhashref->{$kw}[3] = $value; # for debugging
}