实现贷款迁徙从关注转次级的向下迁移

def solve():
    from pyodide.http import open_url
    clients_csv = open_url(____).read()
    loans_csv = open_url(____).read()
    loan_classifications_csv = open_url(____).read()
    loan_provisions_csv = open_url(____).read()
    import sqlite3, pandas as pd
    from io import StringIO
    conn = sqlite3.connect(____)
    pd.read_csv(StringIO(____)).to_sql(____)
    before = pd.read_sql_query(____).set_index(____)["____"].to_dict()
    watch_bal = float(before.get(____))
    migrate_amount = watch_bal * ____
    print(____)
    for k, v in sorted(before.items()):
        print(____)
    print()
    print(____)
    after_watch = watch_bal - migrate_amount
    after_sub = float(before.get(____)) + migrate_amount
    print(____)
    conn.close()