code: func DatapointValueToFloat64(value interface{}) (float64, error) {
  	switch value := value.(type) {
  	case float64:
  		return value, nil
  	case float32:
  		return float64(value), nil
  	case int64:
  		return float64(value), nil
  	case int32:
  		return float64(value), nil
  	case int:
  		return float64(value), nil
  	case string:
  		return strconv.ParseFloat(value, 64)
  	}
  	return math.NaN(), fmt.Errorf("Could not convert %+v (%T) to float64", value, value)
  }
docs: // DatapointValueToFloat64 converts a Datapoint's Value from an
  // interface{} to a float64.