text: '''
  How About Stock Returns?
  
  In the last exercise, you showed that Amazon stock prices, contained in the DataFrame AMZN follow a random walk. In this exercise. you will do the same thing for Amazon returns (percent change in prices) and show that the returns do not follow a random walk.
  
  INSTRUCTIONS
  100XP
  Import the adfuller module from statsmodels.
  Create a new DataFrame of AMZN returns by taking the percent change of prices using the method .pct_change().
  Eliminate the NaN in the first row of returns using the .dropna() method on the DataFrame.
  Run the Augmented Dickey-Fuller test on the Adj Close column of the returns DataFrame, and print out the p-value in `results[1].
  '''
  # Import the adfuller module from statsmodels
  from statsmodels.tsa.stattools import adfuller
  
  # Create a DataFrame of AMZN returns
  AMZN_ret = AMZN.pct_change()
  
  # Eliminate the NaN in the first row of returns
  AMZN_ret = AMZN_ret.dropna()
  
  # Run the ADF test on the return series and print out the p-value
  results = adfuller(AMZN_ret['Adj Close'])
  print('The p-value of the test on returns is: ' + str(results[1]))