About the `EasyPredicate` design about einstein HOT 2 OPEN

public enum EasyPredicate: RawRepresentable {
    
    case exists(_ exists: Bool)
    case isEnabled(_ isEnabled: Bool)
    case isHittable(_ isHittable: Bool)
    case isSelected(_ isSelected: Bool)
    case label(_ comparison: Comparison, _ value: String)
    case identifier(_ identifier: String)
    case type(_ type: XCUIElement.ElementType)
    case other(_ ragular: String)
    
    public init?(rawValue: PredicateRawValue) {
        switch rawValue {
        case .bool(let key, _, let value):
            switch key {
            case .exists:       self = .exists(value)
            case .isEnabled:    self = .isEnabled(value)
            case .isSelected:   self = .isSelected(value)
            case .isHittable:   self = .isHittable(value)
            }
        case .type(let value):  self = .type(value)
        case .string(let key, let comparison, let value):
            switch key {
            case .label:        self = .label(comparison, value)
            case .identifier:   self = .identifier(value)
            }
        case .custom(let regular): self = .other(regular)
        }
    }
    
    public var rawValue: PredicateRawValue {
        switch self {
        case .exists(let value):
            return .bool(key: .exists, comparison: .equals, value: value)
        case .isEnabled(let value):
            return .bool(key: .isEnabled, comparison: .equals, value: value)
        case .isHittable(let value):
            return .bool(key: .isHittable, comparison: .equals, value: value)
        case .isSelected(let value):
            return .bool(key: .isSelected, comparison: .equals, value: value)
        case .label(let comparison, let value):
            return .string(key: .label, comparison: comparison, value: value)
        case .identifier(let value):
            return .string(key: .identifier, comparison: .equals, value: value)
        case .type(let value):
            return .type(value: value)
        case .other(let value):
            return .custom(regular: value)
        }
    }
}

struct EasyPredicate {

    typealias BoolRawValue = PredicateRawValue<PredicateKey.bool, Bool>
    typealias StringRawValue = PredicateRawValue<PredicateKey.string, String>
    typealias TypeRawValue = PredicateRawValue<PredicateKey.type, XCUIElement.ElementType>
    
    static func exists(_ exists: Bool) -> BoolRawValue {
        return BoolRawValue.keyValue(key: .exists, comparison: .equals, value: exists)
    }
    static func isEnabled(_ isEnabled: Bool) -> BoolRawValue {
        return BoolRawValue.keyValue(key: .isEnabled, comparison: .equals, value: isEnabled)
    }
    static func isHittable(_ isHittable: Bool) -> BoolRawValue {
        return BoolRawValue.keyValue(key: .isHittable, comparison: .equals, value: isHittable)
    }
    static func isSelected(_ isSelected: Bool) -> BoolRawValue {
        return BoolRawValue.keyValue(key: .isSelected, comparison: .equals, value: isSelected)
    }
    static func type(_ comparison: Comparison, _ value: XCUIElement.ElementType) -> TypeRawValue {
        return TypeRawValue.keyValue(key: .elementType, comparison: comparison, value: value)
    }
    static func label(_ comparison: Comparison, _ value: String) -> StringRawValue {
        return StringRawValue.keyValue(key: .label, comparison: comparison, value: value)
    }
    static func identifier( _ value: String) -> StringRawValue {
        return StringRawValue.keyValue(key: PredicateKey.string.label, comparison: .equals, value: value)
    }
    static func ragular( _ ragular: String) -> StringRawValue {
        return StringRawValue.custom(regular: ragular)
    }
}

extension String: RawRepresentable {
    public var rawValue: String { return self }
    public init?(rawValue: String) {
        self = rawValue
    }
}
extension Bool: RawRepresentable {
    public var rawValue: Bool { return self }
    public init?(rawValue: Bool) {
        self = rawValue
    }
}
extension XCUIElement.ElementType: RawRepresentable {
    public var rawValue: XCUIElement.ElementType { return self }
    public init?(rawValue: XCUIElement.ElementType) {
        self = rawValue
    }
}