code: def simple_merge(kls, skeletons):
      
      if len(skeletons) == 0:
        return PrecomputedSkeleton()
  
      if type(skeletons[0]) is np.ndarray:
        skeletons = [ skeletons ]
  
      ct = 0
      edges = []
      for skel in skeletons:
        edge = skel.edges + ct
        edges.append(edge)
        ct += skel.vertices.shape[0]
  
      return PrecomputedSkeleton(
        vertices=np.concatenate([ skel.vertices for skel in skeletons ], axis=0),
        edges=np.concatenate(edges, axis=0),
        radii=np.concatenate([ skel.radii for skel in skeletons ], axis=0),
        vertex_types=np.concatenate([ skel.vertex_types for skel in skeletons ], axis=0),
        segid=skeletons[0].id,
      )
docs: Simple concatenation of skeletons into one object 
      without adding edges between them.