Analisis efektifitas kegiatan mewarnai untuk menurunkan skor ansietas pre-operatif anak usia sekolah di Ruang Rawat Bedah Anak (BCH) RSUPN Cipto Mangunkusumo = Effectiveness analysis of coloring activities to reduce pre-operative anxiety score of school-age children in the Childrens Surgery Room (BCH) of RSUPN Cipto Mangunkusumo