code: func (ms *MetricSender) SendValue(name string, value float64, unit string) error {
  	return ms.eventEmitter.Emit(&events.ValueMetric{Name: &name, Value: &value, Unit: &unit})
  }
docs: // SendValue sends a metric with the given name, value and unit. See
  // http://metrics20.org/spec/#units for a specification of acceptable units.
  // Returns an error if one occurs while sending the event.