text: #ifndef _PHONEBOOK_H
  #define _PHONEBOOK_H
  
  #define MAX_LAST_NAME_SIZE 16
  
  /* original version */
  typedef struct __PHONE_BOOK_ENTRY {
      char lastName[MAX_LAST_NAME_SIZE];
      char firstName[16];
      char email[16];
      char phone[10];
      char cell[10];
      char addr1[16];
      char addr2[16];
      char city[16];
      char state[2];
      char zip[5];
      struct __PHONE_BOOK_ENTRY *pNext;
  } entry;
  
  entry *findName(char lastName[], entry *pHead);
  entry *append(char lastName[], entry *e);
  void init_memorypool(int size);
  void free_memorypool(void);
  #endif
  