title: How to make Date as first column
body: <p>I have a list data consisting of 500 Dataframes. Each Dataframe have same dimensions. Now I want to add first column as Date in every dataframe.</p>
  
  <p>I have generated date as values. I have tried it using map and lapply. But it does not solve. </p>
  
  <p>Now I want everydataframe having date as first column.</p>