code: public function apply(Scope $scope, GenericList $arguments) {
  		if (is_null($this->index)) {
  			if (count($arguments) == 0) throw new \BadFunctionCallException("ArgumentGet: No index specified.");
  			$index = intval($arguments[0]->evaluate($scope));
  		}
  		else $index = $this->index;
  		
  		if (!array_key_exists($index, $scope->arguments))
  			throw new \UnexpectedValueException(sprintf("ArgumentGet: No parameter found at index %d.", $index));
  		return $scope->arguments[$index];
  	}
docs: Obtains argument at given index
  Usage: (%0) (% _num)
  Returns: mixed
  (non-PHPdoc)
  @see \eMacros\Applicable::apply()