code: public function getIterator() {
  		$symbols = [];
  		
  		foreach ($this->listSymbols() as $name)
  			$symbols[$name] = $this[$name];
  	
  		return new \ArrayIterator($symbols);
  	}
docs: Obtains a symbol iterator
  (non-PHPdoc)
  @see IteratorAggregate::getIterator()