anchor.diff:  peek_char(Pid) ->
     command(Pid, 'peek_char').
   
  -is_char_ready(Pid) ->
  -  command(Pid, 'is_char_ready').
  -
   close_input_port(Pid) ->
     command(Pid, 'close').
   
  
positive.code:   Fns = #input_port_fns
      {close = fun input_file_close/1,
       read_char = fun input_file_read_char/1,
       peek_char = fun input_file_peek_char/1,
       is_char_ready = fun input_file_is_char_ready/1},
    handle_input_port(State, Fns).
  
  input_file_close({_, IoDev}) ->
  
negative.code:       end;
      [Ch | _] ->
        {{ok, Ch}, State}
    end.
  
  %% Generic output port infrastructure
  