internal/storage/postgres/storage.go
func (s *Storage) Collect(in chan<- prometheus.Metric) {
	s.connections.Set(float64(s.db.Stats().OpenConnections))

	s.connections.Collect(in)
	s.queriesTotal.Collect(in)
	s.queriesDuration.Collect(in)
	s.errors.Collect(in)
}
func (s *Storage) Collect(in chan<- prometheus.Metric) {
	s.connections.Set(float64(s.db.Stats().OpenConnections))

	s.connections.Collect(in)
	s.queriesTotal.Collect(in)
	s.queriesDuration.Collect(in)
	s.errors.Collect(in)
}
// Collect implements prometheus Collector interface.