code: function _buildNamespace(appName, depth) {
      var callerFile;
  
      // Our default depth needs to be 2, since 1 is this file. Add the user
      // supplied depth to 1 (for this file) to make it 2.
      callerFile = caller(depth + 1);
  
      // if for some reason we're unable to determine the caller, use the appName only
      if (!callerFile) {
          return appName;
      }
  
      // TODO in later versions of Node (v0.12.+), there is simple `path.parse`
      // which will provide us with the file name property. But until most have
      // moved up to that version, find the caller file name in this way...
  
      // find the filename from the path
      callerFile = path.basename(callerFile);
  
      // strip off the suffix (if any)
      if (path.extname(callerFile)) {
          callerFile = callerFile.slice(0, callerFile.indexOf(path.extname(callerFile)));
      }
  
      return appName + ":" + callerFile;
  }
docs: Returns the descriptive text used in the debug instantiation, which at this
  point is the app + calling filename. Allow the user to specify a depth for the
  calling filename, in the case they have a wrapping function calling this.
  
  @param  {String} appName The application name, used in the namespace
  @param  {Number} depth   Depth used to determine caller filename
  
  @return {String}         The app + calling filename