<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def fetch_31(self):
 """Fetch 31 days data"""

        today = datetime.datetime.today()
        before = today - datetime.timedelta(days=60)
        self.fetch_from(before.year, before.month)
        self.data = self.data[-31:]
        return self.data