p.numRunes += len(re.Rune)
	if re.Op == OpCharClass && len(re.Rune) == 2 && re.Rune[0] == re.Rune[1] {
		// Single rune.
		if p.maybeConcat(re.Rune[0], p.flags&^FoldCase) {
			return nil
		}
		re.Op = OpLiteral
		re.Rune = re.Rune[:1]
		re.Flags = p.flags &^ FoldCase
	} else if re.Op == OpCharClass && len(re.Rune) == 4 &&
		re.Rune[0] == re.Rune[1] && re.Rune[2] == re.Rune[3] &&
		unicode.SimpleFold(re.Rune[0]) == re.Rune[2] &&

	}
}

// methodIndex returns the index of the method with the given name.
// If foldCase is set, capitalization in the name is ignored.
// The result is negative if no such method exists.
func (t *Named) methodIndex(name string, foldCase bool) int {
	if name == "_" {
		return -1
	}
	if foldCase {
		for i, m := range t.methods {
			if strings.EqualFold(m.name, name) {
				return i
			}
		}

	}
}

// methodIndex returns the index of the method with the given name.
// If foldCase is set, capitalization in the name is ignored.
// The result is negative if no such method exists.
func (t *Named) methodIndex(name string, foldCase bool) int {
	if name == "_" {
		return -1
	}
	if foldCase {
		for i, m := range t.methods {
			if strings.EqualFold(m.name, name) {
				return i
			}
		}

// when in fact the algorithm is faster than the standard one.
func Diff(oldName string, old []byte, newName string, new []byte) []byte {
	if bytes.Equal(old, new) {
		return nil
	}
	x := lines(old)
	y := lines(new)

	// Print diff header.
	var out bytes.Buffer
	fmt.Fprintf(&out, "diff %s %s\n", oldName, newName)
	fmt.Fprintf(&out, "--- %s\n", oldName)
	fmt.Fprintf(&out, "+++ %s\n", newName)

	// Loop over matches to consider,

	}
	return err
}

// Symlink creates a symlink newname -> oldname.
func (sh *Shell) Symlink(oldname, newname string) error {
	// It's not an error to try to recreate an existing symlink.
	if link, err := os.Readlink(newname); err == nil && link == oldname {
		return nil
	}

	if cfg.BuildN || cfg.BuildX {
		sh.ShowCmd("", "ln -s %s %s", oldname, newname)
		if cfg.BuildN {
			return nil
		}
	}

	setParent(*Scope)

	// sameId reports whether obj.Id() and Id(pkg, name) are the same.
	// If foldCase is true, names are considered equal if they are equal with case folding
	// and their packages are ignored (e.g., pkg1.m, pkg1.M, pkg2.m, and pkg2.M are all equal).
	sameId(pkg *Package, name string, foldCase bool) bool

	// scopePos returns the start position of the scope of this Object
	scopePos() syntax.Pos

    val currentThread = Thread.currentThread()
    val oldName = currentThread.name
    currentThread.name = task.name

    var delayNanos = -1L
    try {
      delayNanos = task.runOnce()
    } finally {
      lock.withLock {
        afterRun(task, delayNanos)
      }
      currentThread.name = oldName
    }
  }

  private fun afterRun(
    task: Task,

	setParent(*Scope)

	// sameId reports whether obj.Id() and Id(pkg, name) are the same.
	// If foldCase is true, names are considered equal if they are equal with case folding
	// and their packages are ignored (e.g., pkg1.m, pkg1.M, pkg2.m, and pkg2.M are all equal).
	sameId(pkg *Package, name string, foldCase bool) bool

	// scopePos returns the start position of the scope of this Object
	scopePos() token.Pos

  }
}

internal inline fun threadName(
  name: String,
  block: () -> Unit,
) {
  val currentThread = Thread.currentThread()
  val oldName = currentThread.name
  currentThread.name = name
  try {
    block()
  } finally {
    currentThread.name = oldName
  }
}

/** Returns the Content-Length as reported by the response headers. */
internal fun Response.headersContentLength(): Long {

// LookupMethod returns the index of and method with matching package and name, or (-1, nil).
func (s *_TypeSet) LookupMethod(pkg *Package, name string, foldCase bool) (int, *Func) {
	return methodIndex(s.methods, pkg, name, foldCase)
}

func (s *_TypeSet) String() string {
	switch {
	case s.IsEmpty():
		return "∅"
	case s.IsAll():
		return "𝓤"
	}

	hasMethods := len(s.methods) > 0