docs: def prefix(self, prefix='#', *args):
          """
          Prefix one or multiple arguments with a Dockerfile command. The default is ``#``, for comments. Multiple args will
          be separated by a space.
  
          :param prefix: Dockerfile command to use, e.g. ``ENV`` or ``RUN``.
          :type prefix: unicode | str
          :param args: Arguments to be prefixed.
          """
          self.write(prefix)
          if args:
              self.write(' ')
              self.writeline(' '.join(map(six.text_type, args)))