A type that can be represented as a string in a lossless, unambiguous way.
protocol LosslessStringConvertible : CustomStringConvertible
For example, the integer value 1050 can be represented in its entirety as the string “1050”.
The description property of a conforming type must be a value-preserving representation of the original value. As such, it should be possible to re-create an instance from its string representation.