code: func (c *Cursor) node() *node {
  	_assert(len(c.stack) > 0, "accessing a node with a zero-length cursor stack")
  
  	// If the top of the stack is a leaf node then just return it.
  	if ref := &c.stack[len(c.stack)-1]; ref.node != nil && ref.isLeaf() {
  		return ref.node
  	}
  
  	// Start from root and traverse down the hierarchy.
  	var n = c.stack[0].node
  	if n == nil {
  		n = c.bucket.node(c.stack[0].page.id, nil)
  	}
  	for _, ref := range c.stack[:len(c.stack)-1] {
  		_assert(!n.isLeaf, "expected branch node")
  		n = n.childAt(int(ref.index))
  	}
  	_assert(n.isLeaf, "expected leaf node")
  	return n
  }
docs: // node returns the node that the cursor is currently positioned on.