title: Data Structure - For multiple possible keys types, if key is true, return subset of values
body: <p>A quick example:</p>
  
  <pre><code>Tom, Mary and John say "I want an apple"
  Tom and John say "I want a race car"
  John and Mary say "I want a pretty dress."
  
  DataStructure[Tom] returns --&gt; "I want an apple";"I want a racecar";
  DataStructure[Mary] returns --&gt; "I want an apple";"I want a pretty dress";
  </code></pre>
  
  <p>What is the idea data structure?  If the number of keys or values can change?  Where I could presumably type DataStructure.Add(Mary, "New String); or DataStructure.AddWithNewKey("Timmy", List)?</p>
  
  <hr>
  
  <p>Is there a better way than keeping a list or array of strings for each person?</p>
  
  <hr>
  
  <p>In the comments below, I was confused as to why it would matter if the data was known at compile time or was purely dynamic.  Jon has pointed out that if the data was to be built dynamically, the ideal would be a dictionary related the string values to the people.  Otherwise his linq solution is quite nice.</p>