anchor.diff:  type Output = 
    {  /// Required attribute - The name of the task's output parameter.
       TaskParameter : string
  -    Condition : Condition option
  +    Condition     : Condition option
       (*
           PropertyName
           Either the PropertyName or ItemName attribute is required.
  
positive.code:         "$(" and ")". For example, $(builddir)\classes would resolve to 
          "build\classes", if the builddir property had the value build.
      *)
   }
  
  /// Contains a set of user-defined Property elements. Every Property element
  ///  used in an MSBuild project must be a child of a PropertyGroup element.
  //  https://msdn.microsoft.com/en-us/library/t4w159bs.aspx
  type PropertyGroup =
   {  Condition : Condition
      Children : Property list
   }
  
  
  
  
negative.code:     /// New ImportGroup with a different Condition
      member self.WithCondition cond = { self with Condition = Some cond }
  
     
      member private self.display =
          (StringBuilder().AppendLine(
              "Condition : " + (  if Option.isSome self.Condition 
  