func (f Convert) Float64() (float64, error) {
	return strconv.ParseFloat(f.String(), 64)
}
Float64 string to float64
package mapper
import (
	"fmt"
	"math/big"
	"reflect"
	"strconv"
	"time"
)
type Convert string
func (f *Convert) Set(v string) {
	if v != "" {
		*f = Convert(v)
	} else {
		f.Clear()
	}
}
func (f *Convert) Clear() {
	*f = Convert(0x1E)
}
func (f Convert) Exist() bool {
	return string(f) != string(0x1E)
}
func (f Convert) Bool() (bool, error) {
	return strconv.ParseBool(f.String())
}
func (f Convert) Float32() (float32, error) {
	v, err := strconv.ParseFloat(f.String(), 32)
	return float32(v), err
}