title: Concatenate string collection into one string with separator and enclosing characters
body: <p>I have a collection of source strings that I wish to concatenate into one destination string.</p>
  
  <p>The source collection looks as follows:</p>
  
  <pre><code>{ "a", "b", "c" }
  </code></pre>
  
  <p>I want the output string to be:</p>
  
  <pre><code>abc
  </code></pre>
  
  <p>But sometimes, I want a separator as well. So for the same input, now the output is to be:</p>
  
  <pre><code>a-b-c
  </code></pre>
  
  <p>And finally, the input sometimes needs to be enclosed in other characters, in this case <code>[]</code>, causing the output to be:</p>
  
  <pre><code>[a]-[b]-[c]
  </code></pre>
  
  <p>An empty source collection should yield an empty string. How would I go about this?</p>