title: Check if value exists in dataTable?
body: <p>I have DataTable with two columns <em>Author</em> and <em>Bookname</em>.</p>
  
  <p>I want to check if the given string value <em>Author</em> already exists in the DataTable. Is there some built in method to check it, like for Arrays  <code>array.contains</code>?  </p>