What is one trick you can do to avoid the do-catch pyramid of doom? you can return "try method()"

concatenating_errors.swift

enum ErrorEnum: Error {
	case FooError
	case BarError
}

func bar(success: Bool) throws -> String {
	if success {
		return "bar success"
	}
	throw ErrorEnum.BarError
}

func foo(success: (Bool?, Bool)) throws -> String {
	if case(true?) = success.0 {
		return "foo success"
	} else if case(false?) = success.0 {
		return try bar(success: success.1)
	} else {
		throw ErrorEnum.FooError
	}
}

do {
	try foo(success: (true, true)) // "foo success"
} catch ErrorEnum.FooError {
	"foo error"
} catch ErrorEnum.BarError {
	"bar error"
} catch {
	"unhandled error"
}

do {
	try foo(success: (nil, false))
} catch ErrorEnum.FooError {
	"foo error"                   // "foo error"
} catch ErrorEnum.BarError {
	"bar error"
} catch {
	"unhandled error"
}

do {
	try foo(success: (false, true)) // "bar success"
} catch ErrorEnum.FooError {
	"foo error"
} catch ErrorEnum.BarError {
	"bar error"
} catch {
	"unhandled error"
}

do {
	try foo(success: (false, false))
} catch ErrorEnum.FooError {
	"foo error"
} catch ErrorEnum.BarError {
	"bar error"                    // "bar error"
} catch {
	"unhandled error"
}