text: from pypif.obj import ChemicalSystem
  
  def convert(
          files=[],
          important_argument=None,
          whatever_argument=[0.0, 1.0, 2.0],
          do_some_extra_thing=False,
          some_condition=None,
          **kwargs):
      """
      Convert files into a pif
  
      :param files: to convert
      :param important_argument: an important argument, must be provided
      :param whatever_argument: a less important argument with default 1
      :param do_some_extra_thing:
      :param kwargs: any other arguments
      :return: the pif produced by this conversion
      """
      if not important_argument:
          raise KeyError("The important_argument argument was not passed to convert")
      return ChemicalSystem()
  