def customer_item(item_code = nil, code = nil)
      sub_item  = retrieve_item(customer_subscription(code), :items, item_code)
      plan_item = retrieve_item(customer_plan(code),         :items, item_code)
      return nil unless sub_item && plan_item
      item = plan_item.dup
      item[:quantity] = sub_item[:quantity]
      item
    end
def customer_item(item_code = nil, code = nil)
      sub_item  = retrieve_item(customer_subscription(code), :items, item_code)
      plan_item = retrieve_item(customer_plan(code),         :items, item_code)
      return nil unless sub_item && plan_item
      item = plan_item.dup
      item[:quantity] = sub_item[:quantity]
      item
    end
Info about the given item for the given customer.
Merges the plan item info with the subscription item info.

item_code must be provided if the customer is on a plan with more than one item.

code must be provided if this response contains more than one customer.