code: func (v Vars) Value() (driver.Value, error) {
  	m := make(map[string]sql.NullString)
  
  	for k, v := range v {
  		m[string(k)] = sql.NullString{
  			Valid:  true,
  			String: *v,
  		}
  	}
  
  	h := hstore.Hstore{
  		Map: m,
  	}
  
  	return h.Value()
  }
docs: // Value implements the driver.Value interface.