code: func (p *Pool) Get(n, c int) []byte {
  	if n > c {
  		panic("requested length is greater than capacity")
  	}
  
  	pageSize := syscall.Getpagesize()
  	pages := (c+guardSize)/pageSize + 1
  	size := pages * pageSize
  
  	bts := alloc(size)
  
  	g := (*guard)(unsafe.Pointer(&bts[0]))
  	*g = guard{
  		magic:  magic,
  		size:   size,
  		owners: 1,
  	}
  
  	return bts[guardSize : guardSize+n]
  }
docs: // Get returns probably reused slice of bytes with at least capacity of c and
  // exactly len of n.