func NewStringSlice(defaults ...string) *StringSlice {
	return &StringSlice{slice: append([]string{}, defaults...)}
}
NewStringSlice creates a *StringSlice with default values
package cli
import (
	"encoding/json"
	"flag"
	"fmt"
	"strings"
)
type StringSlice struct {
	slice      []string
	hasBeenSet bool
}