code: def process_tessellate(elem, update_delta, delta, **kwargs):
      
      if update_delta:
          elem.delta = delta
          elem.evaluate()
      elem.tessellate(**kwargs)
      return elem
docs: Tessellates surfaces.
  
      .. note:: Helper function required for ``multiprocessing``
  
      :param elem: surface
      :type elem: abstract.Surface
      :param update_delta: flag to control evaluation delta updates
      :type update_delta: bool
      :param delta: evaluation delta
      :type delta: list, tuple
      :return: updated surface
      :rtype: abstract.Surface