public struct SourceAccount {
    public let alias: String
    public let balance: Double
    public let last4: String
    public let sourceProviderId: String

    public init(
        alias: String,
        balance: Double,
        last4: String,
        sourceProviderId: String
    ) {
        self.alias = alias
        self.balance = balance
        self.last4 = last4
        self.sourceProviderId = sourceProviderId
    }
}

private let checkingAccount: SourceAccount = .init(
    alias: "Checking",
    balance: 500.00,
    last4: "1234",
    sourceProviderId: "5163e857-9a05-4170-9d35-d6ad780a0584"
)