code: func (c *chainView) Tip() *blockNode {
  	c.mtx.Lock()
  	tip := c.tip()
  	c.mtx.Unlock()
  	return tip
  }
docs: // Tip returns the current tip block node for the chain view.  It will return
  // nil if there is no tip.
  //
  // This function is safe for concurrent access.