
  -spec erlang:append_element(Tuple1, Term) -> Tuple2
                                 when
                                     Tuple1 :: tuple(),
                                     Tuple2 :: tuple(),
                                     Term :: term().

  Returns a new tuple that has one element more than Tuple1, and
  contains the elements in Tuple1 followed by Term as the last
  element. Semantically equivalent to 
  list_to_tuple(tuple_to_list(Tuple1) ++ [Term]), but much faster.
  Example:

    > erlang:append_element({one, two}, three).
    {one,two,three}
