title: Append string to bytearray
body: <p>I have a byte array, <code>arr</code> and a hexadecimal number <code>a</code>: </p>
  
  <pre><code>arr = bytearray()
  a = 'FE'
  </code></pre>
  
  <p>How can I append this number to bytearray to have the same value, <code>FE</code>? I tried with <code>print(int(a, 16))</code>, but it seems to be a bad idea (it prints <code>254</code> instead of <code>FE</code>).</p>