Update cart.

        Update cart item.
        This method makes a synchronous HTTP request by default. To make an
        asynchronous HTTP request, please pass async=True
        >>> thread = api.update_item(item_id, item, async=True)
        >>> result = thread.get()

        :param async bool
        :param str item_id: Item ID to update. (required)
        :param LineItem item: Line item to update. (required)
        :return: ShoppingCart
                 If the method is called asynchronously,
                 returns the request thread.

def update_item(cls, item_id, item, **kwargs):
        """Update cart.

        Update cart item.
        This method makes a synchronous HTTP request by default. To make an
        asynchronous HTTP request, please pass async=True
        >>> thread = api.update_item(item_id, item, async=True)
        >>> result = thread.get()

        :param async bool
        :param str item_id: Item ID to update. (required)
        :param LineItem item: Line item to update. (required)
        :return: ShoppingCart
                 If the method is called asynchronously,
                 returns the request thread.
        """
        kwargs['_return_http_data_only'] = True
        if kwargs.get('async'):
            return cls._update_item_with_http_info(item_id, item, **kwargs)
        else:
            (data) = cls._update_item_with_http_info(item_id, item, **kwargs)
            return data