-module(town).-behaviour(gen_server).-export([start/0, combine/1]).-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,        code_change/3]).-record(state, {port}).start() ->    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).stop() ->    gen_server:cast(?MODULE, stop).init([]) ->    process_flag(trap_exit, true),    Port = open_port({spawn,              "python -u ./town.py"},        [stream, {line, 1024}]    ),    {ok, #state{port = Port}}.handle_call({combine, Str}, _From, #state{port = Port} = State) ->    io:format("here~n"),    port_command(Port, Str),    receive        {Port, {data, {_Flag, Data}}} ->            io:format("receiving:~p~n", [Data]),            timer:sleep(2000),            {reply, Data, Port}    end.handle_cast(stop, State) ->    {stop, normal, State};handle_cast(_Msg, State) ->    {noreply, State}.handle_info(Info, State) ->    {noreply, State}.terminate(_Reason, Port) ->    ok.code_change(_OldVsn, State, _Extra) ->    {ok, State}.% Internalcombine(_String) ->    start(),    Str = list_to_binary("combine|" ++ _String ++ "\n"),    gen_server:call(?MODULE, {combine, Str}).

#! /usr/bin/python# Filename : town.pyimport sysdef handle(_string):    if _string.startswith("combine|"):        string = "".join(_string[8:].split(","))        return string""" waiting for input"""while 1:    # Recv.Binary Stream as Standard IN    _stream = sys.stdin.readline()    if not _stream:break    inString = _stream.strip("\r\n")    outString = handle(inString)    sys.stdout.write("%s\n" % (outString,))    sys.exit(0)

Eshell V6.2  (abort with ^G)1> town:combine("aaa+bbb").herereceiving:"aaa+bbb""aaa+bbb"2>