code: def save_file(self, filename, encoding='utf8', headers=None,
                    convertors=None, display=True, **kwargs):
          
          global save_file
          
          convertors = convertors or {}
          headers = headers or []
          
          fields = self.get_fields()
          _header = []
          for i, column in enumerate(fields):
              if column.name not in convertors:
                  if display:
                      def f(value, data):
                          return column.get_display_value(value)
  
                      convertors[column.name] = f
              flag = False
              for j in headers:
                  if not isinstance(j, dict):
                      raise ValueError("Header should be a list of dict, but {} type found".format(type(j)))
                  if j['name'] == column.name:
                      _header.append(j)
                      flag = True
                      break
              if not flag:
                  d = {'name':column.name}
                  if display:
                      d['title'] = column.verbose_name or column.name
                  else:
                      d['title'] = column.name
                  _header.append(d)
  
          return save_file(self.run(), filename, encoding=encoding,
                           headers=_header, convertors=convertors, **kwargs)
docs: save result to a csv file.
          display = True will convert value according choices value