title: Lower case an entire string in Racket
body: <p>Is there a way to turn all of the characters in a string into lower case in <a href="http://racket-lang.org/" rel="noreferrer">Racket</a>?</p>
  
  <p>The only way I can think of is turning char-downcase but it won't work with strings</p>
  
  <p>I am using the beginner language so I can't use some functions</p>