code: public function offsetGet($symbol) {		
  		$sym = self::symbol($symbol);
  
  		//is symbol defined on this scope?
  		if (array_key_exists($sym, $this->symbols))
  			return $this->symbols[$sym];
  		else {
  			foreach ($this->macros as $regex => $callback) {
  				if (preg_match($regex, $sym, $matches))
  					return $this->symbols[$sym] = $callback->__invoke($matches);
  			}
  		}
  		
  		return;
  	}
docs: Obtains a symbol from table
  (non-PHPdoc)
  @see ArrayAccess::offsetGet()