title: Go regex, Negative Look Ahead alternative
body: <p>I am trying to implement the regex <code>(?&lt;!\\{)\\[[a-zA-Z0-9_]+\\](?!\\})</code> with go regex. </p>
  
  <p>Match value will be like <code>[ua]</code> and <code>[ua_enc]</code> and unmatched should be <code>{[ua]}</code> and <code>{[ua_enc]}</code></p>
  
  <p>As Negative lookahead is not supported in Go, what may be the alternative expression for this?</p>