anchor.diff:  amz_headers([], L) ->
   	L.
   
  --spec await_response(pid(), reference(), non_neg_integer(), response_handler()) -> any().
  -await_response(Pid, Ref, Timeout, Handle) ->
  -	Mref = monitor(process, Pid),
  -	receive
  -		{gun_response, Pid, Ref, nofin, Status, Headers} ->
  -			Data = await_data(Pid, Ref, Timeout, Mref, <<>>),
  -			demonitor(Mref, [flush]),
  -			gun:flush(Ref),
  -			Handle(Status, Headers, Data);
  -		{gun_response, Pid, Ref, fin, Status, Headers} ->
  -			demonitor(Mref, [flush]),
  -			gun:flush(Ref),
  -			Handle(Status, Headers, <<>>);
  -		{gun_error, Pid, Ref, Reason} ->
  -			demonitor(Mref, [flush]),
  -			gun:flush(Ref),
  -			exit(Reason);
  -		{gun_error, Pid, Reason} ->
  -			demonitor(Mref, [flush]),
  -			gun:flush(Ref),
  -			exit(Reason);
  -		{'DOWN', Mref, process, Pid, Reason} ->
  -			gun:flush(Ref),
  -			exit(Reason)
  -	after Timeout ->
  -		demonitor(Mref, [flush]),
  -		gun:flush(Ref),
  -		exit(timeout)
  -	end.
  -
  --spec await_data(pid(), reference(), non_neg_integer(), reference(), iodata()) -> iodata().
  -await_data(Pid, Ref, Timeout, Mref, Acc) ->
  -	receive
  -		{gun_data, Pid, Ref, nofin, Data} ->
  -			await_data(Pid, Ref, Timeout, Mref, <<Acc/binary, Data/binary>>);
  -		{gun_data, Pid, Ref, fin, Data} ->
  -			<<Acc/binary, Data/binary>>;
  -		{gun_error, Pid, Ref, Reason} ->
  -			demonitor(Mref, [flush]),
  -			gun:flush(Ref),
  -			exit(Reason);
  -		{gun_error, Pid, Reason} ->
  -			demonitor(Mref, [flush]),
  -			gun:flush(Ref),
  -			exit(Reason);
  -		{'DOWN', Mref, process, Pid, Reason} ->
  -			gun:flush(Ref),
  -			exit(Reason)
  -	after Timeout ->
  -		demonitor(Mref, [flush]),
  -		gun:flush(Ref),
  -		exit(timeout)
  -	end.
  -
   -spec parse_resource_bucket(binary()) -> binary().
   parse_resource_bucket(<<$/, Rest/bits>>) ->
   	parse_resource_bucket(Rest, <<>>).
  
positive.code: 
  -spec await(pid(), reference(), non_neg_integer(), response_handler()) -> any().
  await(Pid, Ref, Timeout, Handle) ->
  	await_response(Pid, Ref, Timeout, Handle).
  
  -spec signature_v2(iodata(), iodata(), iodata(), iodata(), headers()) -> iodata().
  signature_v2(Secret, Method, Resource, Date, Headers) ->
  
negative.code: 	put/9,
  	delete/7,
  	await/4,
  	await/5,
  	await_body/5,
  	signature_v2/5,
  	signature_v2/7,
  	access_token_v2/2,
  