This method should never be called outside Chain.
This method should never be called outside Chain.+= or Chain.insert or Chain.remove
A collection of attributes, keyed by the attribute class.
Return the ChainLink "n" positions ahead.
Return the ChainLink "n" positions ahead. If this goes past the end of the Chain, return null.
Return the ChainLink "n" positions behind.
Return the ChainLink "n" positions behind. If this goes past the beginning of the Chain, return null.