rem: p = xmalloc (sizeof (struct successor));
add: p = xmalloc (sizeof *p);
context: record_relation (struct item *j, struct item *k){  struct successor *p;  if (!STREQ (j->str, k->str))    {      k->count++;      p = xmalloc (sizeof (struct successor));      p->suc = k;      p->next = j->top;      j->top = p;    }}