code: def statement_ref_mode(self, value):
          
          valid_values = ['STRICT_KEEP', 'STRICT_KEEP_APPEND', 'STRICT_OVERWRITE', 'KEEP_GOOD', 'CUSTOM']
          if value not in valid_values:
              raise ValueError('Not an allowed reference mode, allowed values {}'.format(' '.join(valid_values)))
  
          self._statement_ref_mode = value
docs: Set the reference mode for a statement, always overrides the global reference state.