anchor.diff:                  | "once" -> ContentCopySettings.OmitIfExisting
                   | _ -> ContentCopySettings.Overwrite
   
  -            ParserOptions(ParserOption.OmitContent(setting))
  -        | String.StartsWith "import_targets" trimmed -> ParserOptions(ParserOption.ImportTargets(trimmed.Replace(":","").Trim() = "true"))
  -        | String.StartsWith "copy_local" trimmed -> ParserOptions(ParserOption.CopyLocal(trimmed.Replace(":","").Trim() = "true"))
  +            Some (ParserOptions(ParserOption.OmitContent(setting)))
  +        | String.StartsWith "import_targets" trimmed -> Some (ParserOptions(ParserOption.ImportTargets(trimmed.Replace(":","").Trim() = "true")))
  +        | String.StartsWith "copy_local" trimmed -> Some (ParserOptions(ParserOption.CopyLocal(trimmed.Replace(":","").Trim() = "true")))
           | String.StartsWith "copy_content_to_output_dir" trimmed -> 
               let setting =
                   match trimmed.Replace(":","").Trim().ToLowerInvariant() with
  
positive.code:                 | "preserve_newest" -> CopyToOutputDirectorySettings.PreserveNewest
                  | x -> failwithf "Unknown copy_content_to_output_dir settings: %A" x
                          
              ParserOptions(ParserOption.CopyContentToOutputDir(setting))
          | String.StartsWith "condition" trimmed -> ParserOptions(ParserOption.ReferenceCondition(trimmed.Replace(":","").Trim().ToUpper()))
          | String.StartsWith "gist" _ as trimmed ->
              SourceFile(parseGitSource trimmed Origin.GistLink "gist")
          | String.StartsWith "github" _ as trimmed  ->
              SourceFile(parseGitSource trimmed Origin.GitHubLink "github")
          | String.StartsWith "git" _ as trimmed  ->
              Git(trimmed.Substring(4))
          | String.StartsWith "file:" _ as trimmed  ->
              Git(trimmed)
          | String.StartsWith "http" _ as trimmed  ->
              SourceFile(parseHttpSource trimmed)
          | String.StartsWith "//" _ -> Empty(line)
          | String.StartsWith "#" _ -> Empty(line)
          | _ -> failwithf "Unrecognized token: %s" line
      
      let parsePackage(sources,parent,name,version,rest:string) =
          let prereleases,optionsText =
  
negative.code:                 | "min" -> Some ResolverStrategy.Min
                  | _ -> None
  
              Some (ParserOptions(ParserOption.ResolverStrategyForTransitives(setting)))
          | String.StartsWith "lowest_matching" trimmed -> 
              let setting =
                  match trimmed.Replace(":","").Trim().ToLowerInvariant() with
  