What does this result builder code produce in `value`?
@resultBuilder
struct SumBuilder {
static func buildBlock(_ parts: Int...) -> Int {
parts.reduce(0, +)
}
static func buildOptional(_ part: Int?) -> Int {
part ?? 0
}
}
func build(@SumBuilder _ body: () -> Int) -> Int { body() }
let flag = false
let value = build {
10
20
if flag { 100 }
}