title: How to check discard custom attribute of method?
body: <p>There is a function call:</p>
  <pre><code>(_, var surname) = Foo(); 
  </code></pre>
  <p>and the function:</p>
  <pre><code>(string Name, string Surname) Foo() 
  {
      // Does the 'Name' attribute have discard symbol?
      ....
  }
  </code></pre>
  <p>Is it possible to know it from runtime?</p>