title: Cannot modify the return value of Dictionary because it is not a variable
body: <p>Have such error: Cannot modify the return value of 'System.Collections.Generic.Dictionary.this[string]' because it is not a variable.`</p>
  
  <p>My code:</p>
  
  <pre><code>Dictionary&lt;string, lim&gt; urlsLimited = new Dictionary&lt;string, lim&gt;();
  struct lim
  {
      public int min;
      public int max;
  }
  void main ()
  {
      ....
      foreach (KeyValuePair&lt;string, lim&gt; pair in urlsLimited)
      {
          string like = od.LikeDiscussions(pair.Key);
          if (like == "Like")
          {
              lock (locker)
              {
                  urlsLimited[pair.Key].min++; // error
  
              }
          }
      }
      ....
  }
  </code></pre>
  
  <p>How to iterate urlsLimited[pair.Key].min++?</p>