title: Add a single backslash ("\") to string in python
body: <p>I have an array of strings which looks like:</p>
  <pre><code>[&quot;U0001f308&quot;, &quot;U0001F602&quot;]
  </code></pre>
  <p>I need to add “\” in front of the first letter U so the output will be like:</p>
  <pre><code>[&quot;\U0001f308&quot;, &quot;\U0001F602&quot;]
  </code></pre>
  <p>This is the code I have tried so far:</p>
  <pre><code>matches = [&quot;U0001f308&quot;, &quot;U0001F602&quot;]
  emojis = [emoji.replace('U', r&quot;\U&quot;) for emoji in matches]
  print(emojis) #this prints ['\\U0001f308', '\\U0001F602'] which has two blacklashes
  </code></pre>
  <p>How can i add only one backslash in front of every string?</p>