def true_code():
    import pandas as pd
    df = pd.read_csv("raw_data/main_data.csv")
    df['Timestamp'] = pd.to_datetime(df['Timestamp'])
    df['Month'] = df['Timestamp'].dt.month_name()
    data = df.groupby("Month")["PM2.5"].mean().idxmax()
    print(data)

true_code()