code: def to_cmd_args(mapping):  # type: (dict) -> list
      
  
      sorted_keys = sorted(mapping.keys())
  
      def arg_name(obj):
          string = _decode(obj)
          if string:
              return u'--%s' % string if len(string) > 1 else u'-%s' % string
          else:
              return u''
  
      arg_names = [arg_name(argument) for argument in sorted_keys]
  
      def arg_value(value):
          if hasattr(value, 'items'):
              map_items = ['%s=%s' % (k, v) for k, v in sorted(value.items())]
              return ','.join(map_items)
          return _decode(value)
  
      arg_values = [arg_value(mapping[key]) for key in sorted_keys]
  
      items = zip(arg_names, arg_values)
  
      return [item for item in itertools.chain.from_iterable(items)]
docs: Transform a dictionary in a list of cmd arguments.
      Example:
          >>>args = mapping.to_cmd_args({'model_dir': '/opt/ml/model', 'batch_size': 25})
          >>>
          >>>print(args)
          ['--model_dir', '/opt/ml/model', '--batch_size', 25]
      Args:
          mapping (dict[str, object]): A Python mapping.
      Returns:
          (list): List of cmd arguments