Step 3.swift

protocol People {
    var people: [Person] { get }
}

@_functionBuilder
struct PeopleBuilder {
    static func buildBlock(_ people: People...) -> [Person] {
        return people.reduce([], {$0+$1.people})
    }
}

struct Person: People {
    let name: String
    let food: Food
    var people: [Person] { [self] }
    init(_ name: String, _ food: Food) {
        self.name = name
        self.food = food
    }
}

struct Family: People {
    let name: String
    private let members: [Person]
    var people: [Person] { members }
    
    // For blocks that return just 1 Person object
    init(_ name: String, @PeopleBuilder _ builder: () -> Person) {
        self.name = name
        self.members = [builder()]
    }
    
    // For blocks that return multiple Person objects
    init(_ name: String, @PeopleBuilder _ builder: () -> [Person]) {
        self.name = name
        self.members = builder()
    }
}

struct Table {
    let people: [Person]
    
    // For blocks that return just 1 Person object
    init(@PeopleBuilder _ builder: () -> Person) {
        self.people = [builder()]
    }
    
    // For blocks that return multiple Person objects
    init(@PeopleBuilder _ builder: () -> [Person]) {
        self.people = builder()
    }
}

Table {
    Family("Mr. & Mrs. Smith") {
        Person("Mr. John Smith", .beef)
        Person("Mrs. Jane Smith", .chicken)
    }
    Person("Mr. Ed Ford", .chicken)
    Person("Mrs. Amanda Doolittle", .vegitarian)
    Family("Mr. & Mrs. Appleseed") {
        Person("Mr. Jonny Appleseed", .chicken)
        Person("Mrs. Jessica Appleseed", .vegitarian)
        Person("Timmy Appleseed", .kids)
    }
    Family("Mr. & Mrs. Doe") {
        Person("Mr. James Doe", .chicken)
        Person("Mrs. Janice Doe", .beef)
        Person("James Doe Jr.", .kids)
    }
}