code: def create_bmi_config_file(self, filename: str = "bmi_config.txt") -> None:
          
          s0 = self.construct_default_initial_state()
          s0.to_csv(filename, index_label="variable")
docs: Create a BMI config file to initialize the model.
  
          Args:
              filename: The filename with which the config file should be saved.