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: meta.go
    path of file: ./repos/goldfish/vendor/github.com/hashicorp/vault/meta
    
    the code of the file until where you have to start completion: package meta

import (
	"bufio"
	"flag"
	"io"
	"os"

	"github.com/hashicorp/vault/api"
	"github.com/hashicorp/vault/command/token"
	"github.com/hashicorp/vault/helper/flag-slice"
	"github.com/mitchellh/cli"
)

// FlagSetFlags is an enum to define what flags are present in the
// default FlagSet returned by Meta.FlagSet.
type FlagSetFlags uint

type TokenHelperFunc func() (token.TokenHelper, error)

const (
	FlagSetNone    FlagSetFlags = 0
	FlagSetServer  FlagSetFlags = 1 << iota
	FlagSetDefault              = FlagSetServer
)

var (
	additionalOptionsUsage = func() string {
		return `
  -wrap-ttl=""            Indicates that the response should be wrapped in a
                          cubbyhole token with the requested TTL. The response
                          can be fetched by calling the "sys/wrapping/unwrap"
                          endpoint, passing in the wrapping token's ID. This
                          is a numeric string with an optional suffix
                          "s", "m", or "h"; if no suffix is specified it will
                          be parsed as seconds. May also be specified via
                          VAULT_WRAP_TTL.

  -policy-override        Indicates that any soft-mandatory Sentinel policies
                          be overridden.
`
	}
)

// Meta contains the meta-options and functionality that nearly every
// Vault command inherits.
type Meta struct {
	ClientToken string
	Ui          cli.Ui

	// The things below can be set, but aren't common
	ForceAddress string // Address to force for API clients

	// These are set by the command line flags.
	flagAddress        string
	flagCACert         string
	flagCAPath         string
	flagClientCert     stri
    
func (m *Meta) Client() (*api.Client, error) {
	config := api.DefaultConfig()

	if m.flagAddress != "" {
		config.Address = m.flagAddress
	}
	if m.ForceAddress != "" {
		config.Address = m.ForceAddress
	}
	// If we need custom TLS configuration, then set it
	if m.flagCACert != "" || m.flagCAPath != "" || m.flagClientCert != "" || m.flagClientKey != "" || m.flagInsecure {
		t := &api.TLSConfig{
			CACert:        m.flagCACert,
			CAPath:        m.flagCAPath,
			ClientCert:    m.flagClientCert,
			ClientKey:     m.flagClientKey,
			TLSServerName: "",
			Insecure:      m.flagInsecure,
		}
		if err := config.ConfigureTLS(t); err != nil {
			return nil, err
		}
	}

	// Build the client
	client, err := api.NewClient(config)
	if err != nil {
		return nil, err
	}

	client.SetWrappingLookupFunc(m.DefaultWrappingLookupFunc)

	var mfaCreds []string

	// Extract the MFA credentials from environment variable first
	if os.Getenv(api.EnvVaultMFA) != "" {
		mfaCreds = []string{os.Getenv(api.EnvVaultMFA)}
	}

	// If CLI MFA flags were supplied, prefer that over environment variable
	if len(m.flagMFA) != 0 {
		mfaCreds = m.flagMFA
	}

	client.SetMFACreds(mfaCreds)

	client.SetPolicyOverride(m.flagPolicyOverride)

	// If we have a token directly, then set that
	token := m.ClientToken

	// Try to set the token to what is already stored
	if token == "" {
		token = client.Token()
	}

	// If we don't have a token, check the token helper
	if token == "" {
		if m.TokenHelper != nil {
			// If we have a token, then set that
			tokenHelper, err := m.TokenHelper()
			if err != nil {
				return nil, err
			}
			token, err = tokenHelper.Get()
			if err != nil {
				return nil, err
			}
		}
	}

	// Set the token
	if token != "" {
		client.SetToken(token)
	}

	return client, nil
}