anchor.diff:       (_)                    -> false
     end.
   
  -option_match_test_() ->
  +match_option_test_() ->
     A  = opt("-a"),
     AT = A#option{value = true},
     X  = opt("-x"),
  
positive.code:   , ?_assertEqual({true , [A]   , [AT]}, match(A, [AT, A]))
    ].
  
  argument_match_test_() ->
    A  = arg("V"),
    AV = arg("V", 9),
    V  = arg(undefined, 9),
  
negative.code:   , ?_assertEqual({true , [V0]    , [AV]}, match(A, [V, V0]))
    ].
  
  match_command_test_() ->
    C  = cmd("c"),
    A  = arg(undefined, "c"),
    CT = cmd("c", true),
  