Solution: Modeling APIs

## Credit-Check Story at BigCo Inc.
We run a simple credit check periodically on companies that are our customers in order to update their 
baseline spending limit and discount percentages.
### Background
Each company record has one or more `account` records. Each `account` record as a `spendingLimit`
property and a `discountPercentage` property. By default, these two values are set to `5000` 
and `5%`, respectively. However, we can modify those values by running a simple credit check 
using the customer name to see if we need to adjust those values up or down.
We have an internal account history that is used to generate suggested ratings for companies we 
deal with. The details on how we generate these numbers is kept secret. 
### Credit Checking
The credit-check service has a safe method called `CreditCheckForm` which accepts a `companyName` and 
returns a `CreditCheckItem` response that contains the property `rating` (a single value between 
1 and 10).  That `rating` value can then be used to determine BigCo's standard `spendingLimit` 
and `discountPercentage` for that company's account record. 
Each time the credit-check service is queried, it also writes a history record called `CreditCheckItem` 
that can be called up later for review. The action `CreditCheckHistory` is recalled using the same 
`companyName` that was used when making the initial credit check. History records contain the 
following properties: `identifier`, `companyName`, `dateRequested`, and `rating`.
We run this credit check when we first add a company account record and once a year after that (on January 1st).