SafetyTier....(_:)

Use the prefix closed range operator (prefix ..) to create a partial range of any type that conforms to the Comparable protocol. This example creates a `PartialRangeThrough<Double>instance that includes any value less than or equal to5.0`.

let throughFive = ...5.0

throughFive.contains(4.0) // true throughFive.contains(5.0) // true throughFive.contains(6.0) // false

You can use this type of partial range of a collection's indices to represent the range from the start of the collection up to, and including, the partial range's upper bound.

let numbers = [10, 20, 30, 40, 50, 60, 70] print(numbers[...3]) // Prints "[10, 20, 30, 40]"

• Parameter maximum: The upper bound for the range.
• Precondition: maximum must compare equal to itself (i.e. cannot be NaN).