It provides a set of quite general list manipulation methods to inheriting classes.
Attributes list Holds an array, the essential content of the object.
Array elements can be, and are in fact frequently, arrays themselves. Only exact matches are returned, but you can use Perls regular expressions. As an alternative, the 'filter' concept is available. It takes a function as the only parameter. This function should expect a list element, and return true or false depending on whether the element matches the criteria.