How do I print an integer in binary with leading zeros? : <p>I'm doing some bit twiddling and I'd like to print all the bits in my u16.</p>

<pre><code>let flags = 0b0000000000101100u16;
println!("flags: {:#b}", flags);
</code></pre>

<p>This prints <code>flags: 0b101100</code>.</p>

<p>How do I make it print <code>flags: 0b0000000000101100</code>?</p>
