title: Extract items of IEnumerable<T> whose Key-Value is equal to one of the KeyValues in IEnumerable<U>
body: <p>I want to extract all items of an IEnumerable sequence whose Key-Value is equal to one of the Key-Values in another IEnumerable sequence.
  Please consider the first sequence is of Type 'T', where T is:</p>
  
  <pre><code>class T
  {
      int SpecificValue;
      // other payload
  }
  </code></pre>
  
  <p>and the second sequence is of Type 'U', where U is:</p>
  
  <pre><code>class U
  {
      int SpecificValueOfSameType;
      // other payload (different from class T)
  }
  </code></pre>
  
  <p>Is it possible?</p>
  
  <p>As a side node: I used the term "Key"-Value, but there's no guarantee that this value is unique in either of both sequences. It should just help to explain my requirements a little bit more in detail. In real code, I can imagine there's some kind of Compare-Func parameter).</p>