some indexes see GH-9
An optimize function.
for each node that has grandchildren in a tree
if the number of children is more than twice the mean of grandchildren per children
for each child
for each grandchild
if it isn't already, put as child
if it isn't already, put the previous child as grandchild through the previous grandchild
transfer the previous children of the granchildren as children of the previous children, checking whether they were already there up to the fact node.
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