title: How to extract string from Mono<String> in reactor core
body: <p>I have a <code>Mono&lt;String&gt;</code> object in reactor. How can I get a string value from this object?</p>
  
  <p>I know I can do something like below :
  For <code>Mono&lt;String&gt; userName</code>, I can do,</p>
  
  <pre><code>userName.map(System.out::println). 
  </code></pre>
  
  <p>But this will directly print the value. I want to store this string value into another variable so that I can pass that variable around to some other functions. How can I extract this value?</p>