title: python re.sub : replace substring with string
body: <p>In python,</p>
  
  <p>with <code>re.sub</code>, how I can replace a substring with a new string ?</p>
  
  <p>from</p>
  
  <pre><code>number = "20"
  s = "hello number 10, Agosto 19"
  </code></pre>
  
  <p>to </p>
  
  <pre><code>s = "hello number 20, Agosto 19"
  </code></pre>
  
  <p>I try</p>
  
  <pre><code>re.sub(r'number ([0-9]*)', number, s)
  </code></pre>
  
  <h3>EDIT</h3>
  
  <p>the number <code>10</code> is a example, the number in the string can be any number.</p>