title: Strip/replace spaces within a string
body: <p>Given a string <code>"5 900 000"</code> </p>
  
  <p>I want to get rid of the spaces using <code>gsub</code> with the following pattern:</p>
  
  <pre><code>gsub(/\s/, '')
  </code></pre>
  
  <p>but that doesn't seem to work. Nor does:</p>
  
  <pre><code>gsub(' ', '')
  </code></pre>