code: public function execute(array $arguments) {
      	if (empty($arguments)) throw new \BadFunctionCallException("Car: No parameters found.");
          list($list) = $arguments;
          
          if ($list instanceof \Iterator) {
              $list->rewind();
              $value = $list->valid() ? $list->current() : null;
          }
          elseif ($list instanceof \IteratorAggregate) {
              $iter = $list->getIterator();
              $iter->rewind();
              $value = $iter->valid() ? $iter->current() : null;
          }
          elseif (is_array($list))
          	$value = !empty($list) ? array_shift($list) : null;
          elseif ($list instanceof \ArrayAccess)
          	$value = isset($list[0]) ? $list[0] : null;
          else
          	throw new \InvalidArgumentException('Car: Parameter is not a list.');
          return $value;
      }
docs: Returns the head element on a list
  Usage: (Array:car (array 1 2 3))
  Returns: mixed
  (non-PHPdoc)
  @see \eMacros\Runtime\GenericFunction::execute()