title: AttributeError: module 'pandas' has no attribute 'ewma'
body: <pre><code>mte_exp_wighted_avg = pd.ewma(mte, halflife=12)
  plt.plot(mte)
  plt.plot(mte_exp_wighted_avg, color='red')
  plt.xticks(fontsize = 25)
  plt.yticks(fontsize = 25)
  plt.xlabel('Years', fontsize = 25)
  plt.ylabel('CO2 Emission', fontsize = 25)
  plt.title('CO2 emission by coal power generation', fontsize = 25)
  plt.show()
  </code></pre>
  
  <p>code is shown above, pandas are upgraded</p>
  
  <p>error is shown below </p>