     return EncodedScalar(_storage: 0xbdbfef, _bitCount: 24)
   }
 
-  public static func _isScalar(_ x: CodeUnit) -> Bool {
+  internal static func _isScalar(_ x: CodeUnit) -> Bool {
     return x & 0x80 == 0
   }
 


  do {
    var iterator = utfStr.makeIterator()
    let errorCount = Codec.ForwardDecoder.decode(
      &iterator, repairingIllFormedSequences: false, into: output1)
    expectEqual(expectedRepairedTail.isEmpty ? 0 : 1, errorCount)
  }


public protocol _UnicodeEncoding : _UnicodeEncodingBase {

  associatedtype ForwardParser : UnicodeParser
  // where ForwardParser.Encoding == Self
  
  associatedtype ReverseParser : UnicodeParser
  // where ReverseParser.Encoding == Self
}

public protocol UnicodeEncoding : _UnicodeEncoding
where ForwardParser.Encoding == Self, ReverseParser.Encoding == Self {}

extension UnicodeParser {
  @inline(__always)
  @discardableResult
  public static func decode<I: IteratorProtocol>(
