title: What is wrong with this pandas code?
body: <pre><code>import pandas as pd
  s1 = pd.Series([1, 2, 3])
  s2 = pd.Series([4, 5, 6])
  s1.append(s2)
  print(s1)
  </code></pre>
  
  <p>Such a simple thing but Its not appending. Out up is :
  0 1
  1 2
  2 3
  dtype: int64
  It just prints s1. Its not appending? What silly mistake am I doing here?</p>