title: Constraint for specific bits
body: <p>I am trying to randomly constrain a 32-bit address.
  Is there a way for me to constraint specific bits of the address?</p>
  
  <pre><code>rand bit [31:0] addr;
  
  // last two bits should always be zero
  
  req.randomize() with { addr[1:0] == 2'b00; };
  </code></pre>