text: import pandas as pd
  from vaderSentiment.vaderSentiment import SentimentIntensityAnalyzer
  
  
  def calc_scores(sentence):
      sid_obj = SentimentIntensityAnalyzer()
      sentiment_dict = sid_obj.polarity_scores(sentence)
      return sentiment_dict
  
  
  def sentiment_scores(df):
      scores = pd.Series(0.0, index=df.index)
      print ("Calculate sentiment scores...")
      for i in df.index:
          row = df.loc[i]["Title"] + ". " + df.loc[i]["Abstract"] + " " + df.loc[i]["Lesson(s) Learned"]
          sentiment_dict = calc_scores(row)
          scores.loc[i] = sentiment_dict['compound']
      print ("Complete.")
      return (-scores + 1) / 2