func (c *MosquittoCounter) Describe(ch chan<- *prometheus.Desc) {
	ch <- c.Desc
}
Describe simply sends the two Descs in the struct to the channel.
package main
import (
	"errors"
	"github.com/prometheus/client_golang/prometheus"
)
type MosquittoCounter struct {
	Desc *prometheus.Desc
	counter
}
func NewMosquittoCounter(desc *prometheus.Desc) *MosquittoCounter {
	return &MosquittoCounter{
		Desc: desc,
	}
}
func (c *MosquittoCounter) Set(v float64) {
	c.counter.Set(v)
}