   /// - Parameters:
   ///   - value: The value to convert to a string.
   ///   - radix: The base to use for the string representation. `radix` must be
-  ///     at least 2 and at most 36.
+  ///     at least 2 and at most 36. The default is 10.
   ///   - uppercase: Pass `true` to use uppercase letters to represent numerals
   ///     greater than 9, or `false` to use lowercase letters. The default is
   ///     `false`.
   public init<T : UnsignedInteger>(
-    _ value: T, radix: Int, uppercase: Bool = false
+    _ value: T, radix: Int = 10, uppercase: Bool = false
   ) {
     _precondition(radix > 1, "Radix must be greater than 1")
     self = _uint64ToString(

  /// - Parameters:
  ///   - value: The value to convert to a string.
  ///   - radix: The base to use for the string representation. `radix` must be
  ///     at least 2 and at most 36.
  ///   - uppercase: Pass `true` to use uppercase letters to represent numerals
  ///     greater than 9, or `false` to use lowercase letters. The default is
  ///     `false`.
  public init<T : _SignedInteger>(
    _ value: T, radix: Int, uppercase: Bool = false
  ) {
    _precondition(radix > 1, "Radix must be greater than 1")
    self = _int64ToString(
      value.toIntMax(), radix: Int64(radix), uppercase: uppercase)
  }
  
  /// Creates a string representing the given value in the specified base.
  ///
  /// Numerals greater than 9 are represented as Roman letters. These letters
  /// start with `"A"` if `uppercase` is `true`; otherwise, with `"a"`.


// Conversions to string from other types.
extension String {
  /// Creates a string representing the given value in base 10, or some other
  /// specified base.
  ///
  /// The following example converts the maximal `Int` value to a string and
  /// prints its length:
