func (this *Output) toStrings(arrayInterface []interface{}) (strings []string) {
	for _, rs := range arrayInterface {
		s, _ := redis.String(rs, nil)
		strings = append(strings, s)
	}
	return
}
convert interface slice to string slice
package gocommend
import "github.com/garyburd/redigo/redis"
type Output struct {
	recNum int
	cSet   collectionSet
}
func (this *Output) Init(collection string, recNum int) error {
	if collection == "" {
		return gocommendError{emptyCollection}
	}
	this.recNum = recNum - 1
	this.cSet = collectionSet{}
	this.cSet.init(collection)
	return nil
}