anchor.diff:          $xml = [xml](Get-Content $_.FullName)
           :allloop foreach( $li in $xml.make.generate.li ){
               foreach( $target in $li.target ){
  +                if( -not $target ){ continue }
                   foreach( $source in $li.source ){
  -                    if( Newer-Than $source $target ){
  +                    if( -not $source ){ continue }
  +                    if( (Newer-Than $source $target) ){
                           Write-Verbose ("$ go generate for {0}" -f
                               (Join-Path $dir $target) )
                           go generate
  
positive.code:             $dir = (Split-Path $_.FullName -Parent)
              $xml = [xml](Get-Content $_.FullName)
              foreach($li in $xml.make.generate.li){
                  foreach($target in $xml.make.generate.li.target){
                      $path = (Join-Path $dir $target)
                      if( Test-Path $path ){
                          Do-Remove $path
  
negative.code: }
  
  function Newer-Than($source,$target){
      if( -not $target ){
          Write-Warning ('Newer-Than: $target is null')
          if( $source ){
              Write-Verbose ('Newer-Than: $source={0}' -f $source)
          }else{
              Write-Warning 'Newer-Than: $source is null'
          }
          return
      }
      if( -not (Test-Path $target) ){
          Write-Verbose ("{0} not found." -f $target)
          return $true
  