What does an _ (underline character) on the left side of a C# lambda operator mean? : <p>What does an _ (underline character) on the left side of a C# lambda operator mean? as in:</p>

<pre><code>        Movment = this.FixedUpdateAsObservable()
        .Select(_ =&gt;
            {
                var x = Input.GetAxis("Horizontal");
                var y = Input.GetAxis("Vertical");
                return new Vector2(x, y).normalized;
            }
        );
</code></pre>
