code: func (p *Pool) Get(n, c int) []byte {
  	if n > c {
  		panic("requested length is greater than capacity")
  	}
  
  	v, x := p.pool.Get(c)
  	if v != nil {
  		bts := v.([]byte)
  		bts = bts[:n]
  		return bts
  	}
  
  	return make([]byte, n, x)
  }
docs: // Get returns probably reused slice of bytes with at least capacity of c and
  // exactly len of n.