You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: typestring.go
    path of file: ./repos/gomacro/go/types
    
    the code of the file until where you have to start completion: // Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file implements printing of types.

package types

import (
	"bytes"
	"fmt"
)

// A Qualifier controls how named package-level objects are printed in
// calls to TypeString, ObjectString, and SelectionString.
//
// These three formatting routines call the Qualifier for each
// package-level object O, and if the Qualifier returns a non-empty
// string p, the object is printed in the form p.O.
// If it returns an empty string, only the object name O is printed.
//
// Using a nil Qualifi
    
func writeTuple(buf *bytes.Buffer, tup *Tuple, variadic bool, qf Qualifier, visited []Type) {
	buf.WriteByte('(')
	if tup != nil {
		for i, v := range tup.vars {
			if i > 0 {
				buf.WriteString(", ")
			}
			if v.name != "" {
				buf.WriteString(v.name)
				buf.WriteByte(' ')
			}
			typ := v.typ
			if variadic && i == len(tup.vars)-1 {
				if s, ok := typ.(*Slice); ok {
					buf.WriteString("...")
					typ = s.elem
				} else {
					// special case:
					// append(s, "foo"...) leads to signature func([]byte, string...)
					if t, ok := typ.Underlying().(*Basic); !ok || t.kind != String {
						panic("internal error: string type expected")
					}
					writeType(buf, typ, qf, visited)
					buf.WriteString("...")
					continue
				}
			}
			writeType(buf, typ, qf, visited)
		}
	}
	buf.WriteByte(')')
}