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: flag.go
    path of file: ./repos/darktile/vendor/github.com/spf13/pflag
    
    the code of the file until where you have to start completion: // Copyright 2009 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.

/*
Package pflag is a drop-in replacement for Go's flag package, implementing
POSIX/GNU-style --flags.

pflag is compatible with the GNU extensions to the
    
func (f *FlagSet) Parse(arguments []string) error {
	if f.addedGoFlagSets != nil {
		for _, goFlagSet := range f.addedGoFlagSets {
			goFlagSet.Parse(nil)
		}
	}
	f.parsed = true

	if len(arguments) < 0 {
		return nil
	}

	f.args = make([]string, 0, len(arguments))

	set := func(flag *Flag, value string) error {
		return f.Set(flag.Name, value)
	}

	err := f.parseArgs(arguments, set)
	if err != nil {
		switch f.errorHandling {
		case ContinueOnError:
			return err
		case ExitOnError:
			fmt.Println(err)
			os.Exit(2)
		case PanicOnError:
			panic(err)
		}
	}
	return nil
}