DiffSlices does a diff on two slices and returns the changes.

GetTypeResource returns the platform.Type for the type_id in the custom field.

New returns a new terraform.ResourceProvider.

ValidateCurrencyCode checks if a currency string is valid according to https://en.wikipedia.org/wiki/ISO_4217.

TypeLocalizedString defined merely for documentation, it basically is just a normal TypeMap but clarifies in the code that it should be used to store a LocalizedString.