code: func (h *Hash) SetBytes(b []byte) {
  	if len(b) > len(h) {
  		b = b[len(b)-HashLength:]
  	}
  
  	copy(h[HashLength-len(b):], b)
  }
docs: // SetBytes sets the hash to the value of b.
  // If b is larger than len(h), b will be cropped from the left.