code: def use_cli(self, config, prefix=None, name="--config", front=True):
          
          if config:
              provider = DictProvider(to_dict(config, prefix=prefix), name=name)
              self.add(provider, front=front)
docs: Args:
              config: Multi-value option, typically tuple from click CLI flag such as --config
              prefix (str | unicode | None): Prefix to add to all parsed keys
              name (str | unicode): Name of cli flag
              front (bool): If True, add provider to front of list