title: creating new column with conditions
body: <p>here is the dataset: <a href="https://www.kaggle.com/emilianito/saheart" rel="nofollow noreferrer">https://www.kaggle.com/emilianito/saheart</a></p>
  <p>here is the question:
  Derive a new column called agegroup from the age column where persons falling in different age ranges are categorized below:
  (0-15): young
  (15-35): adults
  (35-55): mid
  (55+): old</p>
  <p>I tried this:</p>
  <pre><code>sa_heart_df['agegroup'].young = sa_heart_df['age'] &lt;= 15
  </code></pre>
  <p>however this does not work so pls give a answer:)</p>