code: func (c *Cursor) keyValue() ([]byte, []byte, uint32) {
  	ref := &c.stack[len(c.stack)-1]
  	if ref.count() == 0 || ref.index >= ref.count() {
  		return nil, nil, 0
  	}
  
  	// Retrieve value from node.
  	if ref.node != nil {
  		inode := &ref.node.inodes[ref.index]
  		return inode.key, inode.value, inode.flags
  	}
  
  	// Or retrieve value from page.
  	elem := ref.page.leafPageElement(uint16(ref.index))
  	return elem.key(), elem.value(), elem.flags
  }
docs: // keyValue returns the key and value of the current leaf element.