docs: def safe_pdist(arr, *args, **kwargs):
      """
      Kwargs:
          metric = ut.absdiff
      SeeAlso:
          scipy.spatial.distance.pdist
  
      TODO: move to vtool
  
      """
      if arr is None or len(arr) < 2:
          return None
      else:
          import vtool as vt
          arr_ = vt.atleast_nd(arr, 2)
          return spdist.pdist(arr_, *args, **kwargs)