code: func (s *stack) PeekByteArray(idx int32) ([]byte, error) {
  	sz := int32(len(s.stk))
  	if idx < 0 || idx >= sz {
  		str := fmt.Sprintf("index %d is invalid for stack size %d", idx,
  			sz)
  		return nil, scriptError(ErrInvalidStackOperation, str)
  	}
  
  	return s.stk[sz-idx-1], nil
  }
docs: // PeekByteArray returns the Nth item on the stack without removing it.