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Begin work on exercise 23.2
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‎chapter_23/exercise_2/.gitignore‎

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_build

‎chapter_23/exercise_2/rebar.config‎

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{deps, []}.

‎chapter_23/exercise_2/src/lib_primes.erl‎

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%% ---
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%% Excerpted from "Programming Erlang, Second Edition",
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%% published by The Pragmatic Bookshelf.
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%% Copyrights apply to this code. It may not be used to create training material,
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%% courses, books, articles, and the like. Contact us if you are in doubt.
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%% We make no guarantees that this code is fit for any purpose.
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%% Visit http://www.pragmaticprogrammer.com/titles/jaerlang2 for more book information.
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%%---
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-module(lib_primes).
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-export([make_prime/1, is_prime/1, make_random_int/1]).
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make_prime(1) ->%% <label id="make_primes1" />
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lists:nth(random:uniform(4), [2,3,5,7]);
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make_prime(K) whenK>0->%% <label id="make_primes2" />
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new_seed(),
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N=make_random_int(K),
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ifN>3 ->
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io:format("Generating a ~w digit prime ",[K]),
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MaxTries=N-3,
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P1=make_prime(MaxTries, N+1),
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io:format("~n",[]),
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P1;
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true ->
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make_prime(K)
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end. %% <label id="make_primes3" />
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make_prime(0, _) ->%% <label id="prime_loop1" />
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exit(impossible);
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make_prime(K, P) ->
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io:format(".",[]),
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caseis_prime(P) of
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true -> P;
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false -> make_prime(K-1, P+1)
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end. %% <label id="prime_loop2" />
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is_prime(D) whenD<10->
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lists:member(D, [2,3,5,7]);
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is_prime(D) ->
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new_seed(),
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is_prime(D, 100).
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is_prime(D, Ntests) ->
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N=length(integer_to_list(D)) -1,
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is_prime(Ntests, D, N).
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is_prime(0, _, _) ->true; %% <label id="is_prime_1" />
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is_prime(Ntest, N, Len) ->%% <label id="is_prime_2" />
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K=random:uniform(Len),
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%% A is a random number less than K
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A=make_random_int(K),
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if
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A<N ->
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caselib_lin:pow(A,N,N) of
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A -> is_prime(Ntest-1,N,Len);
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_ -> false
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end;
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true ->
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is_prime(Ntest, N, Len)
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end. %% <label id="is_prime_3" />
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%% make_random_int(N) -> a random integer with N digits.
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make_random_int(N) ->new_seed(), make_random_int(N, 0). %% <label id="make_ran_int1" />
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make_random_int(0, D) ->D;
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make_random_int(N, D) ->
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make_random_int(N-1, D*10+ (random:uniform(10)-1)). %% <label id="make_ran_int2" />
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%END:make_ran_int
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new_seed() ->
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{_,_,X} =erlang:now(),
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{H,M,S} =time(),
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H1=H*Xrem32767,
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M1=M*Xrem32767,
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S1=S*Xrem32767,
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put(random_seed,{H1,M1,S1}).
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‎chapter_23/exercise_2/src/prime_tester_worker.erl‎

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%%%-------------------------------------------------------------------
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%%% @doc
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%%% Prime tester gen server implementation. This gen server is the
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%%% actual worker process that performs the computation to determine
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%%% if the number is prime.
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%%% @end
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%%%-------------------------------------------------------------------
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-module(prime_tester_worker).
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-behaviour(gen_server).
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%% API
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-export([start_link/0, is_prime/1]).
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%% gen_server callbacks
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-export([init/1,
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handle_call/3,
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handle_cast/2,
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handle_info/2,
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terminate/2,
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code_change/3]).
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-define(SERVER, ?MODULE).
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-record(state,{}).
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%%%===================================================================
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%%% API
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%%%===================================================================
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%%--------------------------------------------------------------------
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%% @doc
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%% Starts the server
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%%
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%% @spec start_link() ->{ok, Pid} | ignore |{error, Error}
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%% @end
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%%--------------------------------------------------------------------
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start_link() ->
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gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
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is_prime(Number) whenis_integer(Number) ->
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gen_server:call(?MODULE,{is_prime, Number}).
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%%%===================================================================
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%%% gen_server callbacks
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%%%===================================================================
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Initializes the server
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%%
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%% @spec init(Args) ->{ok, State} |
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%%{ok, State, Timeout} |
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%% ignore |
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%%{stop, Reason}
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%% @end
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%%--------------------------------------------------------------------
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init([]) ->
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{ok, #state{}}.
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%%--------------------------------------------------------------------
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%% @private
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%%--------------------------------------------------------------------
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handle_call({is_prime, Number}, _From, State) ->
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% Invoke lib_primes:is_prime to determine if the number is prime or not
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Result=lib_primes:is_prime(Number),
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{reply,{ok, Result}, State};
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handle_call(_Request, _From, State) ->
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Reply=ok,
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{reply, Reply, State}.
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%%--------------------------------------------------------------------
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%% @private
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%%--------------------------------------------------------------------
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handle_cast(_Msg, State) ->
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{noreply, State}.
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%%--------------------------------------------------------------------
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%% @private
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%%--------------------------------------------------------------------
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handle_info(_Info, State) ->
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{noreply, State}.
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%%--------------------------------------------------------------------
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%% @private
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%%--------------------------------------------------------------------
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terminate(_Reason, _State) ->
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ok.
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%%--------------------------------------------------------------------
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%% @private
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%%--------------------------------------------------------------------
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code_change(_OldVsn, State, _Extra) ->
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{ok, State}.
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%%%===================================================================
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%%% Internal functions
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%%%===================================================================

‎chapter_23/exercise_2/src/prime_tester_worker_sup.erl‎

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%%%-------------------------------------------------------------------
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%%% @doc
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%%%
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%%% @end
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%%%-------------------------------------------------------------------
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-module(prime_tester_worker_sup).
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-behaviour(supervisor).
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%% API
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-export([start_link/0]).
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%% Supervisor callbacks
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-export([init/1]).
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-define(SERVER, ?MODULE).
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%%%===================================================================
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%%% API functions
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%%%===================================================================
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%%--------------------------------------------------------------------
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%% @doc
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%% Starts the supervisor
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%%
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%% @end
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%%--------------------------------------------------------------------
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start_link() ->
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supervisor:start_link({local, ?SERVER}, ?MODULE, []).
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%%%===================================================================
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%%% Supervisor callbacks
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%%%===================================================================
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%%--------------------------------------------------------------------
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%% @private
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%%--------------------------------------------------------------------
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init([]) ->
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MaxRestart=5,
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MaxTime=3600,
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M=prime_tester_worker,
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F=start_link,
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A= [],
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{ok,{{simple_one_for_one, MaxRestart, MaxTime},
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[{prime_tester_worker,
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{M,F,A},
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temporary, 5000, worker, [M]}]}}.
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%%%===================================================================
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%%% Internal functions
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%%%===================================================================

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