     /// The unsigned integer representation of string exceeds
     /// 128 bits.
     case StringInputOverflow
-    /// A condition that shouldn't ever happen. Hax0r!
-    case Inconceivable
 }
 // MARK: Data Type
 /// A 128-bit unsigned integer value type.

}
// MARK: - Strideable
extension UInt128: Strideable {
    /// Returns an instance of UInt128 that is the current instance's
    /// value increased by `n` when `n` is positive or decreased
    /// by `n` when `n` is negative.
    public func advancedBy(n: UInt128.Distance) -> UInt128 {
        if n < 0 {
            return self &- UInt128(n * -1)
        }

    /// data type does not exist, so it has to fall back to an IntMax
    /// representation which lacks half of the storage space when end
    /// is less than the value of self.
    public func distanceTo(end: UInt128) -> Stride {
        if end >= self {
            return Stride(end - self)
        }
        return Stride(end) &- Stride(self)
    }
}
// MARK: - IntegerLiteralConvertible
extension UInt128: IntegerLiteralConvertible {
    public typealias IntegerLiteralType = Int
    public init(integerLiteral value: UInt128.IntegerLiteralType) {
        self.init(value)
    }
    public init(_builtinIntegerLiteral value: _MaxBuiltinIntegerType) {
        self.init(UInt64(_builtinIntegerLiteral: value))
    }
}
// MARK: - StringLiteralConvertible
extension UInt128: StringLiteralConvertible {
    public typealias StringLiteralType = String
    public typealias UnicodeScalarLiteralType = String
    public typealias ExtendedGraphemeClusterLiteralType = String
    public init(stringLiteral value: StringLiteralType) {
        self.init()
        do {
            try self = UInt128.fromUnparsedString(value)
        } catch { return }
    }
    // MARK: UnicodeScalarLiteralConvertible
    public init(unicodeScalarLiteral value: UnicodeScalarLiteralType)  {
        self.init(stringLiteral: value)
    }
    // MARK: ExtendedGraphemeClusterLiteralConvertible
    public init(extendedGraphemeClusterLiteral value: ExtendedGraphemeClusterLiteralType) {
        self.init(stringLiteral: value)
    }
}
