enum Choice: CaseIterable {
    case a, b, c, d, e, f
}

// as show here, the closure can return tuple with any labels
let bitMap = Dictionary<Choice, Int>(uniqueKeysWithValues: Choice.allCases.enumerated().map {
    //    (key: $1, value: 1 << $0)   // error: Initializer 'init(uniqueKeysWithValues:)' requires the types '(key: Choice, value: Int)' and '(Choice, Int)' be equivalent
    //    (key: $1, value: $0)    //  !!! exact same tuple as above, now no problem!
          // not bit shift in second parameter, no problem no matter the tuple labels
    (truck: $1, you: $0)      // no matter what the labels are, all no problem!
    //    ($1, 1 << $0)     // this works
})


// but exactly the same as above, here get compile error
let bitMap2 = Dictionary<Choice, Int>(uniqueKeysWithValues: Choice.allCases.enumerated().map {   // Initializer 'init(uniqueKeysWithValues:)' requires the types '(key: Choice, value: Int)' and '(Choice, Int)' be equivalent
          // bit shift 1 << $0 cause problem
    (key: $1, value: 1 << $0)   // <== because of this, shouldn't be a problem as shown up above
})

// small transform compile fine
let bitMap3 = Dictionary<Choice, Int>(uniqueKeysWithValues: Choice.allCases.enumerated().map {
    let n = 1 << $0
    return (key: $1, value: n)   // <== because of this, shouldn't be a problem as shown up above
})

// also compile
let bitMap4 = Dictionary<Choice, Int>(uniqueKeysWithValues: Choice.allCases.enumerated().map {
    let t = (key: $1, value: 1 << $0)
    return t
})