ANSWER:

I need to duplicate the line before rotating the next one in the loop otherwise there is no trace of it.

In C#:

private void RunScript(Curve ln, int x, double angle, ref object A)

 List lns = new List;
 for (int = 0; i<= x; i++)
  
   Curve copy = ln.DuplicateCurve();
   copy.Rotate(angle * i, Vector3d.ZAxis, ln.PointAtEnd);
   lns.Add(copy);
  
}
A = lns;

in VB.net:

Private Sub RunScript(By Val ln As Curve, ByVal x As Integer, ByVal angle As Double, By Ref A as Object)
  Dim lns As New List(Of Curve) ()
  For i As Integer = 0 To x
     Dim nl As Curve = ln.DuplicateCurve()
     nl.Transform(transform.Rotation(angle*i, vector3D.ZAxis, ln.PointAtEnd))
     lns.Add(nl)
  Next
  A = lns
End Sub

by arthurmani from http://stackoverflow.com/questions/10153584