title: TypeError: 'Int64Index' object is not callable
body: <p>Why am I getting this error?</p>
  <pre><code>ticker = 'NFLX'
  price = get_data(ticker, start_date='2020-01-01', end_date=None, index_as_date=bool, interval ='1d')
  price.to_csv(r'D:\Python Stuff\pythonProject\NFLX.csv')
  df = pd.read_csv('NFLX.csv')
  price_list = df['adjclose']
  change = price_list.diff(1)
  
  
  def RSI():
      change.dropna(inplace=True)
      positive = change.copy()
      negative = change.copy()
      positive[positive &lt; 0] = 0
      negative[negative &gt; 0] = 0
  
      RSI_days = 5
  
      average_gain = positive.rolling(window=RSI_days).mean()
      average_loss = abs(negative.rolling(window=RSI_days).mean())
      relative_strength = average_gain/average_loss
      rsi = 100.0-(100.0/(1.0+relative_strength))
      return rsi
  
  relative_strength_index = RSI()
  
  print(relative_strength_index[-6:])
  
  lowest_rsi = min(relative_strength_index[-6:])
  print(lowest_rsi)
  
  index_number = relative_strength_index[-6:].index(lowest_rsi)
  print('index of lowest rsi = ' + index_number)
  </code></pre>
  <p>When I run the code, my error is &quot;TypeError: 'Int64Index' object is not callable&quot;. How can I improve this code to resolve this error?</p>