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: api.go
    path of file: ./repos/go-ethereum/internal/debug
    
    the code of the file until where you have to start completion: // Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package debug interfaces Go runtime debugging facilities.
// This package is mostly glue code making these facilities available
// through the CLI and RPC subsystem. If you want to use them from Go code,
// use package runtime instead.
package debug

import (
	"bytes"
	"errors"
	"io"
	"os"
	"os/user"
	"path/filepath"
	"regexp"
	"runtime"
	"runtim
    
func (*HandlerT) Stacks(filter *string) string {
	buf := new(bytes.Buffer)
	pprof.Lookup("goroutine").WriteTo(buf, 2)

	// If any filtering was requested, execute them now
	if filter != nil && len(*filter) > 0 {
		expanded := *filter

		// The input filter is a logical expression of package names. Transform
		// it into a proper boolean expression that can be fed into a parser and
		// interpreter:
		//
		// E.g. (eth || snap) && !p2p -> (eth in Value || snap in Value) && p2p not in Value
		expanded = regexp.MustCompile(`[:/\.A-Za-z0-9_-]+`).ReplaceAllString(expanded, "`$0` in Value")
		expanded = regexp.MustCompile("!(`[:/\\.A-Za-z0-9_-]+`)").ReplaceAllString(expanded, "$1 not")
		expanded = strings.ReplaceAll(expanded, "||", "or")
		expanded = strings.ReplaceAll(expanded, "&&", "and")
		log.Info("Expanded filter expression", "filter", *filter, "expanded", expanded)

		expr, err := bexpr.CreateEvaluator(expanded)
		if err != nil {
			log.Error("Failed to parse filter expression", "expanded", expanded, "err", err)
			return ""
		}
		// Split the goroutine dump into segments and filter each
		dump := buf.String()
		buf.Reset()

		for _, trace := range strings.Split(dump, "\n\n") {
			if ok, _ := expr.Evaluate(map[string]string{"Value": trace}); ok {
				buf.WriteString(trace)
				buf.WriteString("\n\n")
			}
		}
	}
	return buf.String()
}