title: Does PHP have a DEBUG symbol that can be used in code?
body: <p>Languages like C and even C# (which technically doesn't have a preprocessor) allow you to write code like:</p>
  
  <pre><code>#DEFINE DEBUG
  ...
  
  string returnedStr = this.SomeFoo();
  #if DEBUG
      Debug.WriteLine("returned string =" + returnedStr);
  #endif
  </code></pre>
  
  <p>This is something I like to use in my code as a form of scaffolding, and I'm wondering if PHP has something like this. I'm sure I can emulate this with variables, but I imagine the fact that PHP is interpreted in most cases will not make it easy to strip/remove the debugging code (since its not needed) automatically when executing it.</p>