registry.go
func (r *Registry) Close() error {
	if r.closing == nil {
		return nil
	}
	close(r.closing)
	return <-r.closed
}
func (r *Registry) Close() error {
	if r.closing == nil {
		return nil
	}
	close(r.closing)
	return <-r.closed
}
func ( r * Registry ) Close ( ) error { if r . closing == nil { return nil } close ( r . closing ) return <- r . closed }
// Close flushes all pending data to reporters
// and releases resources.
Close flushes all pending data to reporters and releases resources .