header trailer bwi jfk sfo (aheader trailer pvd bwi jfk sfo (bheader trailer pvd bwi jfk sfo (cfigure adding an element to the front of sequence represented by doubly linked list with header and trailer sentinels(abefore the operation(bafter creating the new node(cafter linking the neighbors to the new node the deletion of nodeportrayed in figure proceeds in the opposite fashion of an insertion the two neighbors of the node to be deleted are linked directly to each otherthereby bypassing the original node as resultthat node will no longer be considered part of the list and it can be reclaimed by the system because of our use of sentinelsthe same implementation can be used when deleting the first or the last element of sequencebecause even such an element will be stored at node that lies between two others header trailer bwi jfk pvd sfo (aheader trailer bwi jfk pvd sfo (bheader trailer bwi jfk sfo (cfigure removing the element pvd from doubly linked list(abefore the removal(bafter linking out the old node(cafter the removal (and garbage collection