func (e Set) ToNumber() float64 {
	return float64(e.Value)
}
ToNumber changes Set to float64 for numeric operation.
package types
import (
	"strconv"
	"strings"
	"github.com/pingcap/errors"
)
var zeroSet = Set{Name: "", Value: 0}
type Set struct {
	Name  string
	Value uint64
}
func (e Set) String() string {
	return e.Name
}