title: Skip type check on unused parameters
body: <p>When I compile my typescript project, I'm using the <code>noImplicitAny</code> option so that I won't forget to specify the types on my variables and arguments.</p>
  
  <p>However sometimes you have arguments that you don't use. For example:</p>
  
  <pre><code>jQuery.ajaxTransport("+*", function (options: JQueryAjaxSettings) {
    return {
      abort: function (_, callback: JQueryCallback) { 
  </code></pre>
  
  <p>I am not interested in the first argument of the abort function, so I ignore it by naming it _.</p>
  
  <p>Is that the proper way to do that in TypeScript? I couldn't find it in the guide. I suspect that it isn't the proper way, because I can only name one argument _.</p>
  
  <p>Typescript raises the following error:  </p>
  
  <blockquote>
    <p>error TS7006: Parameter '_' implicitly has an 'any' type.</p>
  </blockquote>
  
  <p>I could just type <code>_:any</code> but that seems a bit overkill for an argument that I don't use.</p>