Create a solution for the ACME Supermarket problem.

ACME's quest for global domination has prompted us to open a supermarket – we sell only three products:

Product code        Name            Price

FR1                 Fruit tea       £ 3.11
SR1                 Strawberries    £ 5.00
CF1                 Coffee          £11.23

Our CEO is a big fan of buy-one-get-one-free offers and of fruit tea. He wants us to add a rule to do this.

The COO, though, likes low prices and wants people buying strawberries to get a price
discount for bulk purchases. If you buy 3 or more strawberries, the price should drop to £4.50. Our check-out can scan items in any order, and because the CEO and COO change
their minds often, it needs to be flexible regarding our pricing rules.

The interface to our basket looks like this (shown in JavaScript):

var basket = new Basket(pricingRules)
basket.add(item)
basket.add(item)
var price = basket.total()

Implement a basket system that fulfills these requirements in JavaScript.

Test Data:

Basket: FR1, SR1, FR1, CF1
Total price expected: £19.34

Basket: FR1, FR1
Total price expected: £3.11

Basket: SR1, SR1, FR1, SR1
Total price expected: £16.61