import sys

def convert_file(input_filename, output_filename, converter):
	with open(input_filename, 'rb') as input_file:
		content = input_file.read()
		output = converter(content)
		with open(output_filename, 'wb+') as output_file:
			output_file.write(output)

def main(from_ext, to_ext, converter):
	del sys.argv[0]
	if len(sys.argv) == 0:
		print("error: no input files!", file=sys.stderr)
		exit(1)

	for input_filename in sys.argv:
		output_filename = input_filename.removesuffix(f".{from_ext}") + f".{to_ext}"
		convert_file(input_filename, output_filename, converter)