code: def clean(self, data):
          
          cleaned_data = list()
  
          if not isinstance(data, list):
              data = [data]
  
          for item in data:
              date = datetime.datetime.strptime(item['Date'], '%Y-%m-%d').date()
              cleaned_data.append(dict(price=item['Adj_Close'], date=date))
  
          return cleaned_data
docs: Method returns cleaned list of stock closing prices
          (i.e. dict(date=datetime.date(2015, 1, 2), price='23.21')).