title: How to resolve ??AttributeError: 'NoneType' object has no attribute 'head'
body: <p>I am working with stock data from Google, Apple, and Amazon. All the stock data was downloaded from yahoo finance in CSV format. I have a file named GOOG.csv containing the Google stock data, a file named AAPL.csv containing the Apple stock data, and a file named AMZN.csv containing the Amazon stock data. I am getting an error when I am trying to check the output of the data frame.</p>
  
  <pre><code>google_stock = google_stock.rename(columns={'Adj Close':'google_stock'},inplace=True)
  
  # Change the Adj Close column label to Apple
  apple_stock = apple_stock.rename(columns={'Adj Close':'apple_stock'},inplace=True)
  
  # Change the Adj Close column label to Amazon
  amazon_stock = amazon_stock.rename(columns={'Adj Close':'amazon_stock'},inplace=True)
  
  google_stock.head()```
  
  
  ---------------------------------------------------------------------------
  AttributeError                            Traceback (most recent call last)
  &lt;ipython-input-29-b562791246eb&gt; in &lt;module&gt;()
        1 # We display the google_stock DataFrame
  ----&gt; 2 google_stock.head()
  
  AttributeError: 'NoneType' object has no attribute 'head'
  </code></pre>