code: func (c *StatsdClient) FGaugeDelta(stat string, value float64) error {
  	if value < 0 {
  		return c.send(stat, "%g|g", value, 1)
  	}
  	return c.send(stat, "+%g|g", value, 1)
  }
docs: // FGaugeDelta -- Send a floating point change for a gauge