element before:
MultiCompositeElement[
ContainedElements = [
LeafElementA, BinaryCompositeElement[
Left = LeafElementA
Right = LeafElementA
], LeafElementB
]
]
element after:
MultiCompositeElement[
ContainedElements = [
LeafElementB, MultiCompositeElement[
ContainedElements = [
LeafElementB, LeafElementB, LeafElementA
]
], LeafElementB, LeafElementA
]
]