code: def default_params(model, update_dict=None):
      
  
      if model in parameters:
          params = parameters[model].copy()
      else:
          params = None
  
      if update_dict:
          if params is None:
              params = {}
          params.update(update_dict)
  
      return params
docs: Loads and updates default model parameters
  
      Parameters
      ----------
  
      model : str
          The name of a model
  
      update_dict : dict
          A dict to update default parameters
  
      Returns
      ----------
  
      params : dict
          A dictionary of parameters