title: How to check if a string is blank in Elixir
body: <p>I mean a string is blank if it's empty or contains whitespaces only.
  For example, <code>""</code>, <code>" "</code> and <code>"\n"</code> are all blank.</p>
  
  <p>In Rails, we have the <code>.blank?</code> method. </p>
  
  <p>Is there something similar in Elixir (or in the Phoenix Framework)?</p>