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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _image_url(array, fmt='png', mode="data", quality=90, domain=None):
 """Create a data URL representing an image from a PIL.Image. Args: image: a numpy mode: presently only supports "data" for data URL Returns: URL representing image """

  supported_modes = ("data")
  if mode not in supported_modes:
    message = "Unsupported mode '%s', should be one of '%s'."
    raise ValueError(message, mode, supported_modes)

  image_data = serialize_array(array, fmt=fmt, quality=quality)
  base64_byte_string = base64.b64encode(image_data).decode('ascii')
  return "data:image/" + fmt.upper() + ";base64," + base64_byte_string