title: Multiple pandas.dataframe to one csv file
body: <p>I have multiple pandas dataframes, and hope to write them as one CSV file. What is the most straightforward way?</p>
  
  <p>For example, from following four dataframes,</p>
  
  <p><img src="https://i.stack.imgur.com/Ke90f.png" alt="enter image description here"> </p>
  
  <p>how can I create below CSV?</p>
  
  <p><img src="https://i.stack.imgur.com/vsptx.png" alt="enter image description here"></p>
  
  <p><strong>Note</strong> The dataframes all have the same dimensions.</p>