def where(order_id, options = {})
      _, _, root = @client.get("/orders/#{order_id}/line_items", options)

      root[:items].map{ |item| LineItem.new(item[:data]) }
    end
def where(order_id, options = {})
      _, _, root = @client.get("/orders/#{order_id}/line_items", options)

      root[:items].map{ |item| LineItem.new(item[:data]) }
    end
Retrieve order's line items

 get '/orders/{order_id}/line_items'

 Returns all line items associated to order

 @param order_id [Integer] Unique identifier of a Order
 @param options [Hash] Search options
 @option options [String] :ids Comma-separated list of line item IDs to be returned in a request.
 @option options [Integer] :quantity Quantity of line item.
 @option options [Integer] :value Value of line item.
 @option options [Integer] :page (1) Page number to start from. Page numbering starts at 1, and omitting the `page` parameter will return the first page.
 @option options [Integer] :per_page (25) Number of records to return per page. Default limit is *25* and the maximum number that can be returned is *100*.
 @option options [String] :sort_by (id:asc) A field to sort by. **Default** ordering is **ascending**. If you want to change the sort ordering to descending, append `:desc` to the field e.g. `sort_by=value:desc`.
 @return [Array<LineItem>] The list of LineItems for the first page, unless otherwise specified.