title: C# Check if List contains a custom object with the same value
body: <p>I have a custom object (the properties must be strings):</p>
  
  <pre><code>public class Nemesis
  {
      public String Dex_ID;
      public String Value;
  }
  </code></pre>
  
  <p>I have a certain function, which creates new instances of that object, adds values to them and then adds them to this List:</p>
  
  <pre><code>private List&lt;Nemesis&gt; _nemesisList;
  public List&lt;Nemesis&gt; NemesisList
  {
      get { return _nemesisList; }
      set { _nemesisList = value; }
  }
  </code></pre>
  
  <p>Normally, I'd use this to check for existing things:</p>
  
  <pre><code>if (!NemesisList.Contains(nemesis))
  {
      NemesisList.Add(nemesis);
  }
  </code></pre>
  
  <p>But this time I want to check if my List already contains a <strong>nemesis</strong> with the same <strong>nemesis.Dex_ID</strong>. How do I do that?</p>