code: def _get_tuple(self, fields):
      
      v1 = ''
      v2 = ''
      if len(fields) > 0:
        v1 = fields[0]
      if len(fields) > 1:
        v2 = fields[1]
      return v1, v2
docs: :param fields: a list which contains either 0,1,or 2 values
      :return: a tuple with default values of '';