--AaB03x
content-disposition: form-data; name="foo"

bar
--AaB03x
content-disposition: form-data; name="files"
content-type: multipart/mixed, boundary=BbC04y

--BbC04y
content-disposition: attachment; filename="file.txt"
content-type: text/plain

contents
--BbC04y
content-disposition: attachment; filename="flowers.jpg"
content-type: image/jpeg
content-transfer-encoding: binary

contents
--BbC04y--
--AaB03x--
