code: func (f Float) MarshalJSON() ([]byte, error) {
  	if !f.Valid {
  		return []byte(nullString), nil
  	}
  	return []byte(strconv.FormatFloat(f.Float64, 'f', -1, 64)), nil
  }
docs: // MarshalJSON implements json.Marshaler.
  // It will encode null if this Float is null.