$8.$ Section $15\mathrm{.}2$ describes a file, stack.c$,$ that provides functions for storing integers in a stack. In that section, the stack was implemented as an array. Modify stack.c so that a stack is now stored as a linked list. Replace the contents and top variables by a single variable that points to the first node in the list $($the "top" of the stack$).$ Write the functions in stack.c so that they use this pointer. Remove the is$\_$full function, instead having push return either true $($if memory was available to create a node$)$ or false $($if not$).$