title: How to generate strings based on column values in pandas
body: <p>I have the following df</p>
  <pre><code>   age
  0   6
  1   20
  2   80
  </code></pre>
  <p>I want to create another column that inserts <code>age</code> in the middle of a string. I tried the following, but I did not get my desired output.</p>
  <pre><code>df['x'] = 'They are' + str(age) + 'years old.'
  </code></pre>
  <p>This is my desired output</p>
  <pre><code>   age            x
  0   6   'They are 6 years old'
  1   20  'They are 20 years old'
  2   80  'They are 80 years old'
  
  </code></pre>