按时间顺序划分训练集和测试集

def solve():
    from pyodide.http import open_url
    from io import StringIO
    loans_raw_csv = open_url(____).read()
    loans_clean_csv = open_url(____).read()
    import pandas as pd
    from io import StringIO
    df = pd.read_csv(StringIO(____))
    df = df.sort_values(____).reset_index(____)
    n=len(____); split=int(____)
    train=df.iloc[:split]; test=df.iloc[split:]
    print(____)
    print(____)