This works fine...

arrowc.py

        with open("a.s", "w") as asm_temp:
            asm_temp.write(get_asm(source_file))
            asm_temp.write(get_lib())
        with open("a.s", "r") as asm_temp:
            log("> Compiling with gcc...")
            subprocess.call(["gcc",
                             "-m32",
                             "-o", output_file.name,
                             asm_temp.name
                             ])