func (hc *HexColor) Decode(hexCode string) error {
	var col, err = Hex(hexCode)
	if err != nil {
		return err
	}
	*hc = HexColor(col)
	return nil
}
Decode - deserialize function for https://github.com/kelseyhightower/envconfig
package colorful
import (
	"database/sql/driver"
	"encoding/json"
	"fmt"
	"reflect"
)
type HexColor Color
type errUnsupportedType struct {
	got  interface{}
	want reflect.Type
}
func (hc *HexColor) Scan(value interface{}) error {
	s, ok := value.(string)
	if !ok {
		return errUnsupportedType{got: reflect.TypeOf(value), want: reflect.TypeOf("")}
	}
	c, err := Hex(s)
	if err != nil {
		return err
	}
	*hc = HexColor(c)
	return nil
}
func (hc *HexColor) Value() (driver.Value, error) {
	return Color(*hc).Hex(), nil
}
func (e errUnsupportedType) Error() string {
	return fmt.Sprintf("unsupported type: got %v, want a %s", e.got, e.want)
}
func (hc *HexColor) UnmarshalJSON(data []byte) error {
	var hexCode string
	if err := json.Unmarshal(data, &hexCode); err != nil {
		return err
	}
	var col, err = Hex(hexCode)
	if err != nil {
		return err
	}
	*hc = HexColor(col)
	return nil
}
func (hc HexColor) MarshalJSON() ([]byte, error) {
	return json.Marshal(Color(hc).Hex())
}