def METHOD_NAME():
  verts = np.array([
    [0,0,0], [0,1,0],
    [1,0,0], [1,1,0],
    [2,0,0], [2,1,0],
    [3,0,0], [3,1,0], 
    [3,0,0],
    [4,0,0], [4,1,0],
    [4,0,0],          # duplicate in x direction
    [5,0,0], [5,1,0],
    [5,0,0],
    [6,0,0], [6,1,0], [6,1,2],
    [7,0,0], [7,1,0],
    [4,0,0]
  ], dtype=np.float32)
  faces = np.array([ 
    [0,1,2], [2,3,4], [4,5,6], [7,8,9],
    [9,10,11], [10,11,12],
    [12,13,14], [14,15,16], [15,16,17],
    [15,18,19], [18,19,20]
  ], dtype=np.uint32)
  mesh = Mesh(verts, faces, segid=666)
  def deduplicate(mesh, x, offset_x=0):
    return mesh.deduplicate_chunk_boundaries(
      (x, 100, 100), is_draco=False, 
      offset=(offset_x,-1,-1) # so y=0,z=0 isn't a chunk boundary
    )
  # test that triple 4 isn't affected
  mesh2 = deduplicate(mesh, x=4)
  assert not np.all(mesh.vertices == mesh2.vertices)
  assert mesh2.vertices.shape[0] == mesh.vertices.shape[0] 
  # pop off the last 4
  mesh.vertices = mesh.vertices[:-1]
  mesh.faces = mesh.faces[:-1]
  # test that 4 is now affected
  mesh2 = deduplicate(mesh, x=4)
  assert mesh != mesh2
  assert mesh2.vertices.shape[0] == mesh.vertices.shape[0] - 1
  mesh2 = deduplicate(mesh, x=3)
  assert mesh != mesh2
  assert mesh2.vertices.shape[0] == mesh.vertices.shape[0] - 1
  mesh2 = deduplicate(mesh, x=4, offset_x=-1)
  assert mesh != mesh2
  assert mesh2.vertices.shape[0] == mesh.vertices.shape[0] - 1
  mesh2 = deduplicate(mesh, x=5)
  assert mesh != mesh2
  assert mesh2.vertices.shape[0] == mesh.vertices.shape[0] - 1
  mesh2 = deduplicate(mesh, x=1)
  assert mesh != mesh2
  assert mesh2.vertices.shape[0] == mesh.vertices.shape[0] - 3