code: def update_not_existing_kwargs(to_update, update_from):
      
      if to_update is None:
          to_update = {}
      to_update.update({k:v for k,v in update_from.items() if k not in to_update})
      return to_update
docs: This function updates the keyword aguments from update_from in
      to_update, only if the keys are not set in to_update.
  
      This is used for updated kwargs from the default dicts.