 
   public static func decodeOne(_ encodedScalar: Buffer) -> UnicodeScalar {
     let bits = encodedScalar._storage
-    /*
-    if _fastPath(bits & 0x80 == 0) {
-      _sanityCheck(encodedScalar.count == 1)
-      _sanityCheck(bits == bits & 0xff)
-      return UnicodeScalar(_unchecked: bits)
-    }
-    */
-    
     switch encodedScalar._bitCount {
     case 8: return UnicodeScalar(_unchecked: bits)
     case 16:



public protocol _UTF8Decoder : UnicodeDecoder {
  func _validateBuffer() -> (valid: Bool, length: UInt8)
  var buffer: Buffer { get set }
}


    } while buffer._bitCount < 32

    // Find one unicode scalar.
    let (valid, length) = _parseNonASCII()
    _sanityCheck(1...4 ~= length)
    _sanityCheck(length <= buffer.count)
    
