 Appending one linked list to another can be inefficient unless a reference to the tail is kept as part of the List structure, because we must traverse the entire first list in order to find the tail, and then append the second list to this.Thus, if two linearly linked lists are each of length formula_4, list appending has asymptotic time complexity of formula_8.In the Lisp family of languages, list appending is provided by the codice_12 procedure.