Prevalens hipereaktivitas bronkus pada penyakit paru obstruktif kronik (PPOK) stabil menurut panduan GOLD 2017 di Rumah Sakit Rujukan Respirasi Nasional Persahabatan Jakarta, Indonesia = Prevalence of bronchial hyperreactivity in stable COPD patients according to GOLD 2017 treated at Persahabatan Hospital Jakarta, Indonesia