title: Code Implementation for Class Diagram in UML
body: <p><em>Update 3</em></p>
  
  <p>What do the signs (single line, diamond with star, and arrow) mean in graph (From Eric's ddd book p195) below:</p>
  
  <p><img src="https://i.stack.imgur.com/qaMQE.png" alt="enter image description here"></p>
  
  <p>Any code sample to illustrate would be appreciated.</p>