import json

files = ['es-songs.json', 'es-artists.json', 'es-albums.json']

ids = []
bad_lines = {}

for file in files:
    with open(file) as fp:
        line = fp.readline()

        while line:
            content = json.loads(line)
            if 'index' in content:
                id = content['index']['_id']
                if id in ids:
                    bad_lines[id] = content
                else:
                    ids.append(id)
            line = fp.readline()

if not bad_lines:
    print("No duplicate ID's found, everything's fine!!")
else:
    print('KO')
    print(bad_lines)