code: func RecordMetric(name string, value float64) (int, error) {
  	cname := C.CString(name)
  	defer C.free(unsafe.Pointer(cname))
  	return errNo(C.newrelic_record_metric(cname, C.double(value)))
  }
docs: /*
   * Record a custom metric.
   *
   * @param   name  the name of the metric
   * @param   value   the value of the metric
   * @return  0 on success, else negative warning code or error code
   */