Merge branch 'ks/strengthen-specs' into dev

* ks/strengthen-specs:
  lists: Strengthen and modernize specs
  syntax_tools: Fix an erroneous type and strengthen some specs
  ordsets: Export ordset/1 type and strengthen specs
  compiler: Strengthen some specs to shut off dialyzer warnings

6 files changed, 63 insertions, 67 deletions

diff --git a/lib/compiler/src/cerl.erl b/lib/compiler/src/cerl.erl
index d1fd9d40e2..4b74d60e9f 100644
--- a/lib/compiler/src/cerl.erl
+++ b/lib/compiler/src/cerl.erl
@@ -973,7 +973,7 @@ atom_name(Node) ->
 
 %% TODO: replace the use of the unofficial 'write_string/2'.
 
--spec atom_lit(cerl()) -> string().
+-spec atom_lit(cerl()) -> nonempty_string().
 
 atom_lit(Node) ->
     io_lib:write_string(atom_name(Node), $'). %' stupid Emacs.
@@ -1079,7 +1079,7 @@ char_val(Node) ->
 %%
 %% @see c_char/1
 
--spec char_lit(c_literal()) -> string().
+-spec char_lit(c_literal()) -> nonempty_string().
 
 char_lit(Node) ->
     io_lib:write_char(char_val(Node)).
@@ -1178,7 +1178,7 @@ string_val(Node) ->
 %%
 %% @see c_string/1
 
--spec string_lit(c_literal()) -> string().
+-spec string_lit(c_literal()) -> nonempty_string().
 
 string_lit(Node) ->
     io_lib:write_string(string_val(Node)).
diff --git a/lib/stdlib/src/lists.erl b/lib/stdlib/src/lists.erl
index 431e5b114e..c669c1f7c1 100644
--- a/lib/stdlib/src/lists.erl
+++ b/lib/stdlib/src/lists.erl
@@ -358,7 +358,7 @@ merge(L) ->
 %% merge3(X, Y, Z) -> L
 %%  merges three sorted lists X, Y and Z
 
--spec merge3([_], [_], [_]) -> [_].
+-spec merge3([X], [Y], [Z]) -> [(X | Y | Z)].
 
 merge3(L1, [], L3) ->
    merge(L1, L3);
@@ -370,7 +370,7 @@ merge3(L1, [H2 | T2], [H3 | T3]) ->
 %% rmerge3(X, Y, Z) -> L
 %%  merges three reversed sorted lists X, Y and Z
 
--spec rmerge3([_], [_], [_]) -> [_].
+-spec rmerge3([X], [Y], [Z]) -> [(X | Y | Z)].
 
 rmerge3(L1, [], L3) ->
    rmerge(L1, L3);
@@ -382,7 +382,7 @@ rmerge3(L1, [H2 | T2], [H3 | T3]) ->
 %% merge(X, Y) -> L
 %%  merges two sorted lists X and Y
 
--spec merge([_], [_]) -> [_].
+-spec merge([X], [Y]) -> [(X | Y)].
 
 merge(T1, []) ->
     T1;
@@ -394,7 +394,7 @@ merge(T1, [H2 | T2]) ->
 
 %% reverse(rmerge(reverse(A),reverse(B))) is equal to merge(I,A,B).
 
--spec rmerge([_], [_]) -> [_].
+-spec rmerge([X], [Y]) -> [(X | Y)].
 
 rmerge(T1, []) ->
     T1;
@@ -420,12 +420,12 @@ thing_to_list(X) when is_list(X)    -> X.	%Assumed to be a string
 %% flatten(List, Tail)
 %%  Flatten a list, adding optional tail.
 
--spec flatten([_]) -> [_].
+-spec flatten([term()]) -> [term()].
 
 flatten(List) when is_list(List) ->
     do_flatten(List, []).
 
--spec flatten([_], [_]) -> [_].
+-spec flatten([term()], [term()]) -> [term()].
 
 flatten(List, Tail) when is_list(List), is_list(Tail) ->
     do_flatten(List, Tail).
@@ -440,7 +440,7 @@ do_flatten([], Tail) ->
 %% flatlength(List)
 %%  Calculate the length of a list of lists.
 
--spec flatlength([_]) -> non_neg_integer().
+-spec flatlength([term()]) -> non_neg_integer().
 
 flatlength(List) ->
     flatlength(List, 0).
@@ -481,7 +481,7 @@ flatlength([], L) -> L.
 %    keysearch3(Key, N, T);
 %keysearch3(Key, N, []) -> false.
 
--spec keydelete(_, pos_integer(), [T]) -> [T].
+-spec keydelete(term(), pos_integer(), [T]) -> [T] when T :: tuple().
 
 keydelete(K, N, L) when is_integer(N), N > 0 ->
     keydelete3(K, N, L).
@@ -491,7 +491,7 @@ keydelete3(Key, N, [H|T]) ->
     [H|keydelete3(Key, N, T)];
 keydelete3(_, _, []) -> [].
 
--spec keyreplace(_, pos_integer(), [_], tuple()) -> [_].
+-spec keyreplace(term(), pos_integer(), [tuple()], tuple()) -> [tuple()].
 
 keyreplace(K, N, L, New) when is_integer(N), N > 0, is_tuple(New) ->
     keyreplace3(K, N, L, New).
@@ -502,7 +502,8 @@ keyreplace3(Key, Pos, [H|T], New) ->
     [H|keyreplace3(Key, Pos, T, New)];
 keyreplace3(_, _, [], _) -> [].
 
--spec keytake(_, pos_integer(), [_]) -> {'value', tuple(), [_]} | 'false'.
+-spec keytake(term(), pos_integer(), [tuple()]) ->
+	{'value', tuple(), [tuple()]} | 'false'.
 
 keytake(Key, N, L) when is_integer(N), N > 0 ->
     keytake(Key, N, L, []).
@@ -513,7 +514,8 @@ keytake(Key, N, [H|T], L) ->
     keytake(Key, N, T, [H|L]);
 keytake(_K, _N, [], _L) -> false.
 
--spec keystore(_, pos_integer(), [_], tuple()) -> [_].
+-spec keystore(term(), pos_integer(), [tuple()], tuple()) -> [tuple(),...].
+
 keystore(K, N, L, New) when is_integer(N), N > 0, is_tuple(New) ->
     keystore2(K, N, L, New).
 
@@ -524,7 +526,7 @@ keystore2(Key, N, [H|T], New) ->
 keystore2(_Key, _N, [], New) ->
     [New].
 
--spec keysort(pos_integer(), [T]) -> [T] when is_subtype(T, tuple()).
+-spec keysort(pos_integer(), [T]) -> [T] when T :: tuple().
 
 keysort(I, L) when is_integer(I), I > 0 ->
     case L of
@@ -582,7 +584,7 @@ keysort_1(_I, X, _EX, [], R) ->
     lists:reverse(R, [X]).
 
 -spec keymerge(pos_integer(), [X], [Y]) ->
-	     [R] when is_subtype(X, tuple()), is_subtype(Y, tuple()), is_subtype(R, tuple()).
+	[R] when X :: tuple(), Y :: tuple(), R :: tuple().
 
 keymerge(Index, T1, L2) when is_integer(Index), Index > 0 -> 
     case L2 of
@@ -597,7 +599,7 @@ keymerge(Index, T1, L2) when is_integer(Index), Index > 0 ->
 %% reverse(rkeymerge(I,reverse(A),reverse(B))) is equal to keymerge(I,A,B).
 
 -spec rkeymerge(pos_integer(), [X], [Y]) ->
-	     [R] when is_subtype(X, tuple()), is_subtype(Y, tuple()), is_subtype(R, tuple()).
+	[R] when X :: tuple(), Y :: tuple(), R :: tuple().
 
 rkeymerge(Index, T1, L2) when is_integer(Index), Index > 0 -> 
     case L2 of
@@ -609,7 +611,7 @@ rkeymerge(Index, T1, L2) when is_integer(Index), Index > 0 ->
 	    lists:reverse(M, [])
     end.
 
--spec ukeysort(pos_integer(), [T]) -> [T] when is_subtype(T, tuple()).
+-spec ukeysort(pos_integer(), [T]) -> [T] when T :: tuple().
 
 ukeysort(I, L) when is_integer(I), I > 0 ->
     case L of
@@ -675,7 +677,7 @@ ukeysort_1(_I, X, _EX, []) ->
     [X].
 
 -spec ukeymerge(pos_integer(), [X], [Y]) ->
-	     [(X | Y)] when is_subtype(X, tuple()), is_subtype(Y, tuple()).
+	[(X | Y)] when X :: tuple(), Y :: tuple().
 
 ukeymerge(Index, L1, T2) when is_integer(Index), Index > 0 ->
     case L1 of
@@ -690,7 +692,7 @@ ukeymerge(Index, L1, T2) when is_integer(Index), Index > 0 ->
 %% reverse(rukeymerge(I,reverse(A),reverse(B))) is equal to ukeymerge(I,A,B).
 
 -spec rukeymerge(pos_integer(), [X], [Y]) ->
-	     [(X | Y)] when is_subtype(X, tuple()), is_subtype(Y, tuple()).
+	[(X | Y)] when X :: tuple(), Y :: tuple().
 
 rukeymerge(Index, T1, L2) when is_integer(Index), Index > 0 ->
     case L2 of
@@ -702,7 +704,7 @@ rukeymerge(Index, T1, L2) when is_integer(Index), Index > 0 ->
 	    lists:reverse(M, [])
     end.
 
--spec keymap(fun((_) -> _), pos_integer(), [tuple()]) -> [tuple()].
+-spec keymap(fun((term()) -> term()), pos_integer(), [tuple()]) -> [tuple()].
 
 keymap(Fun, Index, [Tup|Tail]) ->
    [setelement(Index, Tup, Fun(element(Index, Tup)))|keymap(Fun, Index, Tail)];
@@ -725,7 +727,7 @@ sort(Fun, [X, Y | T]) ->
 	    fsplit_2(Y, X, Fun, T, [], [])
     end.
 
--spec merge(fun((X, Y) -> boolean()), [X], [Y]) -> [_].
+-spec merge(fun((X, Y) -> boolean()), [X], [Y]) -> [(X | Y)].
 
 merge(Fun, T1, [H2 | T2]) when is_function(Fun, 2) ->
     lists:reverse(fmerge2_1(T1, H2, Fun, T2, []), []);
@@ -734,7 +736,7 @@ merge(Fun, T1, []) when is_function(Fun, 2) ->
 
 %% reverse(rmerge(F,reverse(A),reverse(B))) is equal to merge(F,A,B).
 
--spec rmerge(fun((X, Y) -> boolean()), [X], [Y]) -> [_].
+-spec rmerge(fun((X, Y) -> boolean()), [X], [Y]) -> [(X | Y)].
 
 rmerge(Fun, T1, [H2 | T2]) when is_function(Fun, 2) ->
     lists:reverse(rfmerge2_1(T1, H2, Fun, T2, []), []);
@@ -768,7 +770,7 @@ usort_1(Fun, X, [Y | L]) ->
 	    ufsplit_2(Y, L, Fun, [X])
     end.
                     
--spec umerge(fun((X, Y) -> boolean()), [X], [Y]) -> [_].
+-spec umerge(fun((X, Y) -> boolean()), [X], [Y]) -> [(X | Y)].
 
 umerge(Fun, [], T2) when is_function(Fun, 2) ->
     T2;
@@ -777,7 +779,7 @@ umerge(Fun, [H1 | T1], T2) when is_function(Fun, 2) ->
 
 %% reverse(rumerge(F,reverse(A),reverse(B))) is equal to umerge(F,A,B).
 
--spec rumerge(fun((X, Y) -> boolean()), [X], [Y]) -> [_].
+-spec rumerge(fun((X, Y) -> boolean()), [X], [Y]) -> [(X | Y)].
 
 rumerge(Fun, T1, []) when is_function(Fun, 2) ->
     T1;
@@ -851,7 +853,7 @@ umerge(L) ->
 %%  merges three sorted lists X, Y and Z without duplicates, 
 %%  removes duplicates
 
--spec umerge3([_], [_], [_]) -> [_].
+-spec umerge3([X], [Y], [Z]) -> [(X | Y | Z)].
 
 umerge3(L1, [], L3) ->
    umerge(L1, L3);
@@ -864,7 +866,7 @@ umerge3(L1, [H2 | T2], [H3 | T3]) ->
 %%  merges three reversed sorted lists X, Y and Z without duplicates,
 %%  removes duplicates
 
--spec rumerge3([_], [_], [_]) -> [_].
+-spec rumerge3([X], [Y], [Z]) -> [(X | Y | Z)].
 
 rumerge3(L1, [], L3) ->
    rumerge(L1, L3);
@@ -876,7 +878,7 @@ rumerge3(L1, [H2 | T2], [H3 | T3]) ->
 %% umerge(X, Y) -> L
 %%  merges two sorted lists X and Y without duplicates, removes duplicates
 
--spec umerge([_], [_]) -> [_].
+-spec umerge([X], [Y]) -> [(X | Y)].
 
 umerge([], T2) ->
     T2;
@@ -889,7 +891,7 @@ umerge([H1 | T1], T2) ->
 
 %% reverse(rumerge(reverse(A),reverse(B))) is equal to umerge(I,A,B).
 
--spec rumerge([_], [_]) -> [_].
+-spec rumerge([X], [Y]) -> [(X | Y)].
 
 rumerge(T1, []) ->
     T1;
@@ -952,13 +954,13 @@ flatmap(F, [Hd|Tail]) ->
     F(Hd) ++ flatmap(F, Tail);
 flatmap(F, []) when is_function(F, 1) -> [].
 
--spec foldl(fun((T, _) -> _), _, [T]) -> _.
+-spec foldl(fun((T, term()) -> term()), term(), [T]) -> term().
 
 foldl(F, Accu, [Hd|Tail]) ->
     foldl(F, F(Hd, Accu), Tail);
 foldl(F, Accu, []) when is_function(F, 2) -> Accu.
 
--spec foldr(fun((T, _) -> _), _, [T]) -> _.
+-spec foldr(fun((T, term()) -> term()), term(), [T]) -> term().
 
 foldr(F, Accu, [Hd|Tail]) ->
     F(Hd, foldr(F, Accu, Tail));
@@ -998,14 +1000,14 @@ zf(F, [Hd|Tail]) ->
     end;
 zf(F, []) when is_function(F, 1) -> [].
 
--spec foreach(F :: fun((T) -> _), List :: [T]) -> 'ok'.
+-spec foreach(F :: fun((T) -> term()), List :: [T]) -> 'ok'.
 
 foreach(F, [Hd|Tail]) ->
     F(Hd),
     foreach(F, Tail);
 foreach(F, []) when is_function(F, 1) -> ok.
 
--spec mapfoldl(fun((T, _) -> {_, _}), _, [T]) -> {[_], _}.
+-spec mapfoldl(fun((A, term()) -> {B, term()}), term(), [A]) -> {[B], term()}.
 
 mapfoldl(F, Accu0, [Hd|Tail]) ->
     {R,Accu1} = F(Hd, Accu0),
@@ -1013,7 +1015,7 @@ mapfoldl(F, Accu0, [Hd|Tail]) ->
     {[R|Rs],Accu2};
 mapfoldl(F, Accu, []) when is_function(F, 2) -> {[],Accu}.
 
--spec mapfoldr(fun((T, _) -> {_, _}), _, [T]) -> {[_], _}.
+-spec mapfoldr(fun((A, term()) -> {B, term()}), term(), [A]) -> {[B], term()}.
 
 mapfoldr(F, Accu0, [Hd|Tail]) ->
     {Rs,Accu1} = mapfoldr(F, Accu0, Tail),
diff --git a/lib/stdlib/src/ordsets.erl b/lib/stdlib/src/ordsets.erl
index e992b66714..4c72e351d0 100644
--- a/lib/stdlib/src/ordsets.erl
+++ b/lib/stdlib/src/ordsets.erl
@@ -26,12 +26,14 @@
 -export([subtract/2,is_subset/2]).
 -export([fold/3,filter/2]).
 
+-export_type([ordset/1]).
+
 -type ordset(T) :: [T].
 
 %% new() -> Set.
 %%  Return a new empty ordered set.
 
--spec new() -> ordset(term()).
+-spec new() -> [].
 
 new() -> [].
 
@@ -84,7 +86,7 @@ is_element(_, []) -> false.
 %% add_element(Element, OrdSet) -> OrdSet.
 %%  Return OrdSet with Element inserted in it.
 
--spec add_element(term(), ordset(_)) -> ordset(_).
+-spec add_element(E, ordset(T)) -> [T | E,...].
 
 add_element(E, [H|Es]) when E > H -> [H|add_element(E, Es)];
 add_element(E, [H|_]=Set) when E < H -> [E|Set];
@@ -94,7 +96,7 @@ add_element(E, []) -> [E].
 %% del_element(Element, OrdSet) -> OrdSet.
 %%  Return OrdSet but with Element removed.
 
--spec del_element(term(), ordset(_)) -> ordset(_).
+-spec del_element(term(), ordset(T)) -> ordset(T).
 
 del_element(E, [H|Es]) when E > H -> [H|del_element(E, Es)];
 del_element(E, [H|_]=Set) when E < H -> Set;
@@ -104,7 +106,7 @@ del_element(_, []) -> [].
 %% union(OrdSet1, OrdSet2) -> OrdSet
 %%  Return the union of OrdSet1 and OrdSet2.
 
--spec union(ordset(_), ordset(_)) -> ordset(_).
+-spec union(ordset(T1), ordset(T2)) -> ordset(T1 | T2).
 
 union([E1|Es1], [E2|_]=Set2) when E1 < E2 ->
     [E1|union(Es1, Set2)];
@@ -118,7 +120,7 @@ union(Es1, []) -> Es1.
 %% union([OrdSet]) -> OrdSet
 %%  Return the union of the list of ordered sets.
 
--spec union([ordset(_)]) -> ordset(_).
+-spec union([ordset(T)]) -> ordset(T).
 
 union([S1,S2|Ss]) ->
     union1(union(S1, S2), Ss);
@@ -206,7 +208,7 @@ is_subset(_, []) -> false.
 %% fold(Fun, Accumulator, OrdSet) -> Accumulator.
 %%  Fold function Fun over all elements in OrdSet and return Accumulator.
 
--spec fold(fun((_, _) -> _), _, ordset(_)) -> _.
+-spec fold(fun((T, term()) -> term()), term(), ordset(T)) -> term().
 
 fold(F, Acc, Set) ->
     lists:foldl(F, Acc, Set).
@@ -214,7 +216,7 @@ fold(F, Acc, Set) ->
 %% filter(Fun, OrdSet) -> OrdSet.
 %%  Filter OrdSet with Fun.
 
--spec filter(fun((_) -> boolean()), ordset(_)) -> ordset(_).
+-spec filter(fun((T) -> boolean()), ordset(T)) -> ordset(T).
 
 filter(F, Set) ->
     lists:filter(F, Set).
diff --git a/lib/syntax_tools/src/erl_syntax.erl b/lib/syntax_tools/src/erl_syntax.erl
index a40bf83c5a..9df5f26454 100644
--- a/lib/syntax_tools/src/erl_syntax.erl
+++ b/lib/syntax_tools/src/erl_syntax.erl
@@ -1818,7 +1818,7 @@ char_value(Node) ->
 %%
 %% @see char/1
 
--spec char_literal(syntaxTree()) -> string().
+-spec char_literal(syntaxTree()) -> nonempty_string().
 
 char_literal(Node) ->
     io_lib:write_char(char_value(Node)).
@@ -1908,7 +1908,7 @@ string_value(Node) ->
 %%
 %% @see string/1
 
--spec string_literal(syntaxTree()) -> string().
+-spec string_literal(syntaxTree()) -> nonempty_string().
 
 string_literal(Node) ->
     io_lib:write_string(string_value(Node)).
diff --git a/lib/syntax_tools/src/erl_syntax_lib.erl b/lib/syntax_tools/src/erl_syntax_lib.erl
index daef74e874..97dfbfd7cd 100644
--- a/lib/syntax_tools/src/erl_syntax_lib.erl
+++ b/lib/syntax_tools/src/erl_syntax_lib.erl
@@ -49,10 +49,6 @@
 -export_type([info_pair/0]).
 
 %% =====================================================================
-
--type ordset(X) :: [X].  % XXX: TAKE ME OUT
-
-%% =====================================================================
 %% @spec map(Function, Tree::syntaxTree()) -> syntaxTree()
 %%
 %%          Function = (syntaxTree()) -> syntaxTree()
@@ -480,7 +476,7 @@ new_variable_names(0, Names, _, _, _) ->
 %% @see annotate_bindings/1
 %% @see //stdlib/ordsets
 
--spec annotate_bindings(erl_syntax:syntaxTree(), ordset(atom())) ->
+-spec annotate_bindings(erl_syntax:syntaxTree(), ordsets:ordset(atom())) ->
         erl_syntax:syntaxTree().
 
 annotate_bindings(Tree, Env) ->
diff --git a/lib/syntax_tools/src/igor.erl b/lib/syntax_tools/src/igor.erl
index 7ec62f1dba..aa933eb54b 100644
--- a/lib/syntax_tools/src/igor.erl
+++ b/lib/syntax_tools/src/igor.erl
@@ -119,20 +119,16 @@
 
 %% =====================================================================
 
--type ordset(X) :: [X].  % XXX: TAKE ME OUT
-
-%% =====================================================================
-
 %% Data structure for module information
 
 -record(module, {name        :: atom(),
 		 vars = none :: [atom()] | 'none',
-		 functions   :: ordset({atom(), arity()}),
-		 exports     :: ordset({atom(), arity()})
-			      | ordset({{atom(), arity()}, term()}),
-		 aliases     :: ordset({{atom(), arity()},
-					{atom(), {atom(), arity()}}}),
-		 attributes  :: ordset({atom(), term()}),
+		 functions   :: ordsets:ordset({atom(), arity()}),
+		 exports     :: ordsets:ordset({atom(), arity()})
+			      | ordsets:ordset({{atom(), arity()}, term()}),
+		 aliases     :: ordsets:ordset({{atom(), arity()},
+						{atom(), {atom(), arity()}}}),
+		 attributes  :: ordsets:ordset({atom(), term()}),
 		 records     :: [{atom(), [{atom(), term()}]}]
 		}).
 
@@ -149,7 +145,7 @@ default_printer(Tree, Options) ->
 -type moduleName()     :: atom().
 -type functionName()   :: {atom(), arity()}.
 -type functionPair()   :: {functionName(), {moduleName(), functionName()}}.
--type stubDescriptor() :: [{moduleName(), [functionPair()], [attribute()]}].
+-type stubDescriptor() :: {moduleName(), [functionPair()], [attribute()]}.
 
 -type notes() :: 'always' | 'yes' | 'no'.
 
@@ -209,7 +205,7 @@ parse_transform(Forms, Options) ->
 %% @spec merge(Name::atom(), Files::[filename()]) -> [filename()]
 %% @equiv merge(Name, Files, [])
 
--spec merge(atom(), [file:filename()]) -> [file:filename()].
+-spec merge(atom(), [file:filename()]) -> [file:filename(),...].
 
 merge(Name, Files) ->
     merge(Name, Files, []).
@@ -343,7 +339,7 @@ merge(Name, Files) ->
 	 {suffix, ?DEFAULT_SUFFIX},
 	 {verbose, false}]).
 
--spec merge(atom(), [file:filename()], [option()]) -> [file:filename()].
+-spec merge(atom(), [file:filename()], [option()]) -> [file:filename(),...].
 
 merge(Name, Files, Opts) ->
     Opts1 = Opts ++ ?DEFAULT_MERGE_OPTS,
@@ -484,7 +480,7 @@ merge_files(Name, Trees, Files, Opts) ->
 %%
 %%     Forms = syntaxTree() | [syntaxTree()]
 %%
-%% @type stubDescriptor() = [{ModuleName, Functions, [Attribute]}]
+%% @type stubDescriptor() = {ModuleName, Functions, [Attribute]}
 %%	    ModuleName = atom()
 %%	    Functions = [{FunctionName, {ModuleName, FunctionName}}]
 %%	    FunctionName = {atom(), integer()}
@@ -687,15 +683,15 @@ merge_files(Name, Trees, Files, Opts) ->
 %% Data structure for merging environment.
 
 -record(merge, {target     :: atom(),
-		sources    :: ordset(atom()),
-		export     :: ordset(atom()),
-		static     :: ordset(atom()),
-		safe       :: ordset(atom()),
+		sources    :: ordsets:ordset(atom()),
+		export     :: ordsets:ordset(atom()),
+		static     :: ordsets:ordset(atom()),
+		safe       :: ordsets:ordset(atom()),
 		preserved  :: boolean(),
 		no_headers :: boolean(),
 		notes      :: notes(),
 		redirect   :: dict(),	% = dict(atom(), atom())
-		no_imports :: ordset(atom()),
+		no_imports :: ordsets:ordset(atom()),
 		options	   :: [option()]
 	       }).