Change:
A node in the tree may also be _blank_, indicating that no value is present at that node.  The _resolution_ of a node is an ordered list of non-blank nodes that collectively cover all non-blank descendants <del> of the node.  The nodes in a resolution are ordered according to their indices. </del> <ins> of the node. </ins> <del> The resolution of a non-blank node is a one element list containing the node itself </del> <ins> The resolution of a non-blank node comprises the node itself, followed by its list of unmerged leaves, if any </ins> The resolution of a blank leaf node is the empty list

Discussion:
This PR attempts to implement the "non-destructive add" proposal discussed at IETF 105. Instead of blanking nodes on add, we keep track of "unmerged leaves" below each intermediate node. This involves a bit more complexity in the tree state that is passed around, but avoids unnecessary blank nodes.
As discussed in the interim: Remove processing should be updated such that for each node in the removed node's direct path: If the removed leaf is in for the node, then just remove it from that list Otherwise, blank the node
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Here's the Weekly Digest for : - - Last week 18 issues were created. Of these, 3 issues have been closed and 15 issues are still open. :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :greenheart: , by :heart: , by :heart: , by :heart: , by :speaker: , by It received 5 comments. - - Last week, 10 pull requests were created, updated or merged. Last week, 1 pull request was opened. :greenheart: , by Last week, 7 pull requests were updated. :yellowheart: , by :yellowheart: , by :yellowheart: , by :yellowheart: , by :yellowheart: , by :yellowheart: , by :yellowheart: , by Last week, 2 pull requests were merged. :purpleheart: , by :purpleheart: , by - - Last week there were 4 commits. :hammerandwrench: by :hammerandwrench: by :hammerandwrench: by :hammerandwrench: by - - Last week there were 4 contributors. :bustinsilhouette: :bustinsilhouette: :bustinsilhouette: :bustin_silhouette: - - Last week there were no stargazers. - - Last week there were no releases. - - That's all for last week, please :eyes: Watch and :star: Star the repository to receive next weekly updates. :smiley: You can also .
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:greenheart: , by :greenheart: , by - - Last week, 8 pull requests were created, updated or merged. Last week, 1 pull request was opened. :greenheart: , by Last week, 5 pull requests were updated. :yellowheart: , by :yellowheart: , by :yellowheart: , by :yellowheart: , by :yellowheart: , by Last week, 2 pull requests were merged. :purpleheart: , by :purpleheart: , by - - Last week there were 2 commits. :hammerandwrench: by :hammerandwrench: by - - Last week there was 1 contributor. :bustinsilhouette: - - Last week there was 1 stargazer. :star: You are the star! :star2: - - Last week there were no releases. - - That's all for last week, please :eyes: Watch and :star: Star the repository to receive next weekly updates. :smiley: You can also .