func (is *incString) Decr() (int64, bool) {
	return is.IncrBy(-1)
}
Decr decrements the value by 1. It returns false as second return value
if the current string value is not numeric.
package types
import "strconv"
type IncString interface {
	String
	Decr() (int64, bool)
	DecrBy(int64) (int64, bool)
	Incr() (int64, bool)
	IncrBy(int64) (int64, bool)
	IncrByFloat(float64) (string, bool)
}
var _ IncString = (*incString)(nil)
type incString struct {
	String
}
func NewIncString(initval string) IncString {
	return &incString{
		NewString(initval),
	}
}