Examples of forward declarations (of functions) in PHP?
<p>I'm posting this because it wasn't readily apparent on Google or php.net</p>

<p>==> <em>Please demonstrate several examples of the <strong>syntax</strong> for <strong>forward declaring</strong> functions, in the <strong>PHP</strong> language.</em></p>

<p>For example (in C++):</p>

<pre><code>int foo(); // forward declaration

int x = foo(); // calling the function.

int foo()  // the actual implementation
{
   return 5;
}
</code></pre>

<p>How would this look in PHP? How about with multiple arguments? How about with default arguments? What are the best practices and why?</p>
