How to get the "text value" and "plane" of an annotation(text) object in rhino?

Hi all,
I need to get the "text value" and "plane" data of all annotations in a model.

(http://www.grasshopper3d.com/forum/topics/get-any-and-all-geometry-...)
I've already looked at the above thread, and learned how to get the objects from a particular layer. But I could only get their ids and I don't know how to transfer them to annotationbase to get the information I want.

here is my code:

  Dim textl As New List(Of Guid)
    Dim tg As IGH_Goo = Nothing

    For Each obj As Rhino.DocObjects.RhinoObject In doc.Objects
      Dim layer As Rhino.DocObjects.Layer = doc.Layers(obj.Attributes.LayerIndex)
      If (layer.Name.Equals(layername, Stringcomparison.Ordinal)) Then
        textl.Add(obj.Id)
      End If
    Next 

    Dim anno As New list(Of annotationbase)
   
    ids = textl
    stringOut = anno

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Thank you!
Chin-Yi Cheng