code: def get_ext(self, format=None, **kwargs):
          
          try:
              format = format or self.default_params['format']
              return ".%s" % format.lower()
          except KeyError: pass
docs: Returns new file extension based on a processor's `format` parameter.
          Overwrite if different extension should be set ex: `'.txt'` or `None` if this 
          processor does not change file's extension.