code: public function execute(array $arguments) {
  		if (empty($arguments)) throw new \BadFunctionCallException("FilterHasVar: No parameters found.");
  		if (!isset($arguments[1])) throw new \BadFunctionCallException("FilterHasVar: No filter has been defined.");
  		if (!in_array($arguments[0], self::$filter_types))
  			throw new \InvalidArgumentException(sprintf("FilterHasVar: Filter type '%s' ", strval($arguments[0])));
  		return filter_has_var(self::$filter_types[$arguments[0]], $arguments[1]);
  	}
docs: Checks whether a given index is defined on a global array
  Usage: (has-var POST 'message')
  Returns: boolean
  (non-PHPdoc)
  @see \eMacros\Runtime\GenericFunction::execute()