anchor.diff:  
   t_build_and_match_literals(Config) when is_list(Config) ->
       #{} = id(#{}),
  -    #{1=>a} = id(#{1=>a}),
  -    #{1=>a,2=>b} = id(#{1=>a,2=>b}),
  -    #{1=>a,2=>b,3=>"c"} = id(#{1=>a,2=>b,3=>"c"}),
  -    #{1=>a,2=>b,3=>"c","4"=>"d"} = id(#{1=>a,2=>b,3=>"c","4"=>"d"}),
  -    #{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>} =
  +    #{1:=a} = id(#{1=>a}),
  +    #{1:=a,2:=b} = id(#{1=>a,2=>b}),
  +    #{1:=a,2:=b,3:="c"} = id(#{1=>a,2=>b,3=>"c"}),
  +    #{1:=a,2:=b,3:="c","4":="d"} = id(#{1=>a,2=>b,3=>"c","4"=>"d"}),
  +    #{1:=a,2:=b,3:="c","4":="d",<<"5">>:=<<"e">>} =
   	id(#{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>}),
  -    #{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>,{"6",7}=>"f"} =
  +    #{1:=a,2:=b,3:="c","4":="d",<<"5">>:=<<"e">>,{"6",7}:="f"} =
   	id(#{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>,{"6",7}=>"f"}),
  -    #{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>,{"6",7}=>"f",8=>g} =
  +    #{1:=a,2:=b,3:="c","4":="d",<<"5">>:=<<"e">>,{"6",7}:="f",8:=g} =
   	id(#{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>,{"6",7}=>"f",8=>g}),
   
  -    #{<<"hi all">> => 1} = id(#{<<"hi",32,"all">> => 1}),
  -
  -    #{a=>X,a=>X=3,b=>4} = id(#{a=>3,b=>4}), % weird but ok =)
  -
  -    #{ a=>#{ b=>#{c => third, b=>second}}, b=>first} =
  +    #{<<"hi all">> := 1} = id(#{<<"hi",32,"all">> => 1}),
  +
  +    #{a:=X,a:=X=3,b:=4} = id(#{a=>3,b=>4}), % weird but ok =)
  +
  +    #{ a:=#{ b:=#{c := third, b:=second}}, b:=first} =
   	id(#{ b=>first, a=>#{ b=>#{c => third, b=> second}}}),
   
       M = #{ map_1=>#{ map_2=>#{value_3 => third}, value_2=> second}, value_1=>first},
  -    M = #{ map_1=>#{ map_2=>#{value_3 => third}, value_2=> second}, value_1=>first} =
  +    M = #{ map_1:=#{ map_2:=#{value_3 := third}, value_2:= second}, value_1:=first} =
   	 id(#{ map_1=>#{ map_2=>#{value_3 => third}, value_2=> second}, value_1=>first}),
   
       %% error case
       %V = 32,
       %{'EXIT',{{badmatch,_},_}} = (catch (#{<<"hi all">> => 1} = id(#{<<"hi",V,"all">> => 1}))),
  -    {'EXIT',{{badmatch,_},_}} = (catch (#{x=>3,x=>2} = id(#{x=>3}))),
  -    {'EXIT',{{badmatch,_},_}} = (catch (#{x=>2} = id(#{x=>3}))),
  -    {'EXIT',{{badmatch,_},_}} = (catch (#{x=>3} = id({a,b,c}))),
  -    {'EXIT',{{badmatch,_},_}} = (catch (#{x=>3} = id(#{y=>3}))),
  -    {'EXIT',{{badmatch,_},_}} = (catch (#{x=>3} = id(#{x=>"three"}))),
  +    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3,x:=2} = id(#{x=>3}))),
  +    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=2} = id(#{x=>3}))),
  +    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3} = id({a,b,c}))),
  +    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3} = id(#{y=>3}))),
  +    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3} = id(#{x=>"three"}))),
       ok.
   
   %% Tests size(Map).
  
positive.code: 	{'EXIT',{function_clause,_}} = (catch map_guard_sequence_2(#{b=>5})),
  	ok.
  
  map_guard_sequence_1(#{seq=>1=Seq, val=>Val}) -> {Seq,Val};
  map_guard_sequence_1(#{seq=>2=Seq, val=>Val}) -> {Seq,Val};
  map_guard_sequence_1(#{seq=>3=Seq, val=>Val}) -> {Seq,Val};
  map_guard_sequence_1(#{seq=>4=Seq, val=>Val}) -> {Seq,Val};
  map_guard_sequence_1(#{seq=>5=Seq, val=>Val}) -> {Seq,Val}.
  
  map_guard_sequence_2(#{ a=>3 }=M) -> {1, M};
  map_guard_sequence_2(#{ a=>4 }=M) -> {2, M};
  map_guard_sequence_2(#{ a=>X, a=>X, b=>4 }=M) -> {3,X,M};
  map_guard_sequence_2(#{ a=>X, a=>Y, b=>3 }=M) when X =:= Y -> {4,X,Y,M};
  map_guard_sequence_2(#{ a=>X, a=>Y }=M) when X =:= Y -> {5,X,Y,M}.
  
  
  t_guard_update(Config) when is_list(Config) ->
  
negative.code: 
  
  t_list_comprehension(Config) when is_list(Config) ->
      [#{k:=1},#{k:=2},#{k:=3}] = [#{k:=I} || I <- [1,2,3]],
      ok.
  
  t_guard_fun(Config) when is_list(Config) ->
      F1 = fun
  	    (#{s:=v,v:=V})     -> {v,V};
  	    (#{s:=t,v:={V,V}}) -> {t,V};
  	    (#{s:=l,v:=[V,V]}) -> {l,V}
      end,
      
      F2 = fun
  	    (#{s:=T,v:={V,V}}) -> {T,V};
  	    (#{s:=T,v:=[V,V]}) -> {T,V};
  	    (#{s:=T,v:=V})     -> {T,V}
      end,
      V = <<"hi">>,
  
  