code: def make_writeable(filename):
      
      if not os.access(filename, os.W_OK):
          st = os.stat(filename)
          new_permissions = stat.S_IMODE(st.st_mode) | stat.S_IWUSR
          os.chmod(filename, new_permissions)
docs: Make sure that the file is writeable.
      Useful if our source is read-only.