查询报名人数最多的课程

def solve():
    from pyodide.http import open_url
    from io import StringIO
    import pandas as pd
    enroll_csv = open_url(____).read()
    enroll = pd.read_csv(StringIO(____))
    result = enroll.groupby(____).size().sort_values(____).head(____)
    for course, count in result.items():
        print(____)