code: def image_mime_type(data):
      
      # This checks for a jpeg file with only the magic bytes (unrecognized by
      # imghdr.what). imghdr.what returns none for that type of file, so
      # _wider_test_jpeg is run in that case. It still returns None if it didn't
      # match such a jpeg file.
      kind = _imghdr_what_wrapper(data)
      if kind in ['gif', 'jpeg', 'png', 'tiff', 'bmp']:
          return 'image/{0}'.format(kind)
      elif kind == 'pgm':
          return 'image/x-portable-graymap'
      elif kind == 'pbm':
          return 'image/x-portable-bitmap'
      elif kind == 'ppm':
          return 'image/x-portable-pixmap'
      elif kind == 'xbm':
          return 'image/x-xbitmap'
      else:
          return 'image/x-{0}'.format(kind)
docs: Return the MIME type of the image data (a bytestring).