title: How to pass variable as a column name pandas
body: <p>I'm using Python 2.7
  I try  do create new column based on variable form a list</p>
  
  <p>tickers=['BAC','JPM','WFC','C','MS']
  returns=pd.DataFrame
  for tick in tickers:
       returns[tick]=bank_stocks[tick][<img src="https://i.stack.imgur.com/Bscce.png" alt="[">]<a href="https://i.stack.imgur.com/Bscce.png" rel="nofollow noreferrer">1</a>'Close'].pct_change()**</p>
  
  <h2>But I get this error</h2>
  
  <p>TypeError                                 Traceback (most recent call last)
   in ()
        2 returns=pd.DataFrame
        3 for tick in tickers:
  ----> 4      returns[tick]=bank_stocks[tick]['Close'].pct_change()
        5 </p>
  
  <p>TypeError: 'type' object does not support item assignment</p>