import pandas as pd
import os

def log(hypothesis, result):
    path = "data/log.csv"
    if os.path.exists(path):
        df = pd.read_csv(path)
    else:
        df = pd.DataFrame(columns=['hypothesis','result'])
    df = pd.concat([df, pd.DataFrame({'hypothesis':[hypothesis],'result':[result]})])
    df.to_csv(path, index=False)
    return df.tail(5)