code: func (b *BoundedMemoryChain) Front() *Node {
  	if b.tailPtr == -1 && b.headPtr == -1 {
  		return nil
  	}
  
  	return &b.chain[b.headPtr]
  }
docs: // Front returns the head of the chain. If the chain is empty, then this
  // returns a  pointer to a nil node.
  //
  // NOTE: Part of the Chain interface.