string_prependn (p, s, n) string *p; const char *s; int n;
string_prependn(string *p, const char *s, int n)
string_prependn (p, s, n)     string *p;     const char *s;     int n;{  char *q;  if (n == 0)    return;  string_need (p, n);  for (q = p->p - 1; q >= p->b; q--)    q[n] = q[0];  memcpy (p->b, s, n);  p->p += n;}