title: How to concatenate API request URL safely
body: <p>Let's imagine I have the following parts of a URL:</p>
  
  <pre><code>val url_start = "http://example.com"
  val url_part_1 = "&amp;fields[...]&amp;" //This part of url can be in the middle of url or in the end
  val url_part_2 = "&amp;include..."
  </code></pre>
  
  <p>And then I try to concatenate the resulting URL like this:</p>
  
  <pre><code>val complete_url = url_start + url_part_2 + url_part_1 
  </code></pre>
  
  <p>In this case I'd get <code>http://example.com&amp;include...&amp;fields[...]&amp;</code> (don't consider syntax here), which is one <code>&amp;</code> symbol between URL parts which means that concatenation was successful, <strong>BUT</strong> if I use different concat sequence in a different request like this:</p>
  
  <pre><code>val complete_url = url_start + url_part_1 + url_part_2
  </code></pre>
  
  <p>I'd get <code>http://example.com&amp;fields[...]&amp;&amp;include...</code>, to be specific <code>&amp;&amp;</code> in this case. Is there a way to ensure that concatenation is <em>safer</em>?</p>