Oliver Eyton-Williams 0bd52f8bd1

and change all the challenges to new `md` format.

2020-11-27 10:02:05 -08:00

id, title, challengeType, videoId

id	title	challengeType	videoId
5e9a093a74c4063ca6f7c15d	Data Cleaning Introduction	11	ovYNhnltVxY

--description--

Instead of using notebooks.ai like it shows in the video, you can use Google Colab instead.

More resources:

--question--

What will the following code print out?

import pandas as pd
import numpy as np

s = pd.Series(['a', 3, np.nan, 1, np.nan])

print(s.notnull().sum())

0     True
1     True
2    False
3     True
4    False
dtype: bool

0    False
1    False
2     True
3    False
4     True
dtype: bool