code: def set_elem(elem_ref, elem):
      
      if elem_ref is None or elem_ref == elem or not is_elem_ref(elem_ref):
          return elem
  
      elif elem_ref[0] == ElemRefObj:
          setattr(elem_ref[1], elem_ref[2], elem)
          return elem
  
      elif elem_ref[0] == ElemRefArr:
          elem_ref[1][elem_ref[2]] = elem
          return elem
docs: Sets element referenced by the elem_ref. Returns the elem.
  
      :param elem_ref:
      :param elem:
      :return: