trees :: BinTreeNode :: uncle
# Other child of the `grandparent`
# `left` or `right` depends on the position of the current node against its parent
fun uncle: nullable N do
var g = grandparent
if g == null then
return null
else
if parent == g.left then
return g.right
else
return g.left
end
end
end
lib/trees/bintree.nit:421,2--434,4