Mesh topological identical vertices

Rhino Developer
#1

When does mesh.Vertices.GetTopologicalIndenticalVertices(vertexID); returns null?

File and simple mesh attached.

http://developer.rhino3d.com/api/RhinoCommon/html/M_Rhino_Geometry_Collections_MeshVertexList_GetTopologicalIndenticalVertices.htm

identical
identical.png1686×758 99.3 KB
TopologicalIndeticalVertices.gh (7.7 KB)

Create List in C#
#2

Got it no need for the answer… I had in mind x.TopologyVertices.TopologyVertexIndex(y)