title: `'Column' object is not callable` when showing a single spark column
body: <p>I'm a new spark user, and previously I'm from pandas background. Here's my Spark Dataframe</p>
  
  <pre><code>In[75]:  spDF
  Out[75]: DataFrame[customer_id: string, name: string]
  </code></pre>
  
  <p>and when I <code>show</code> them</p>
  
  <pre><code>In[75]:  spDF.show()
  Out[75]:
  
  +-----------+-----------+
  |customer_id|       name|
  +-----------+-----------+
  |      25620| MCDonnalds|
  |      25620|  STARBUCKS|
  |      25620|        nan|
  |      25620|        nan|
  |      25620| MCDonnalds|
  |      25620|        nan|
  |      25620| MCDonnalds|
  |      25620|DUNKINDONUT|
  |      25620|   LOTTERIA|
  |      25620|        nan|
  |      25620| MCDonnalds|
  |      25620|DUNKINDONUT|
  |      25620|DUNKINDONUT|
  |      25620|        nan|
  |      25620|        nan|
  |      25620|        nan|
  |      25620|        nan|
  |      25620|   LOTTERIA|
  |      25620|   LOTTERIA|
  |      25620|  STARBUCKS|
  +-----------+-----------+
  only showing top 20 rows
  </code></pre>
  
  <p>Then I try querying columns only</p>
  
  <pre><code>In[76]:  spDF['name']
  Out[76]: Column&lt;b'name'&gt;
  </code></pre>
  
  <p>But when I show them, I get the following error.</p>
  
  <pre><code>In[79]: spDF['name'].show()
  ---------------------------------------------------------------------------
  TypeError                                 Traceback (most recent call last)
  &lt;ipython-input-79-f6676d5e5ca2&gt; in &lt;module&gt;()
  ----&gt; 1 spDF['name'].show()
  
  TypeError: 'Column' object is not callable
  </code></pre>
  
  <p>Anyone has an idea, what is this error?</p>