Now, during the simplification of short-circuits the so called
`de-optimization` is also applied to the corresponding `RegionCFGTree`.
This allows us to avoid loss of information during the iterative
refinement phase, which basically divides for ever the existencies of
two nodes that have been cloned starting from a single original one.
After short-circuit simplification, we can have that a conditional node
corresponds to more than one `BasicBlockNode`.
This change reflects this fact, and takes care of merging blocks during
short-circuit simplification, and of representing this change in the
serialization.
Now the `isEqual` operator does what we call a `deep` comparison,
meaning for every type of `ASTNode` it recursively check if the
structures of the AST tree originating in that node can be considered
equivalent (e.g., two sequence nodes are considered equal if every node
they contain is in turn equal).
This operator gives more space to the short-circuit simplification,
which relies heavily on the `isEqual` operator.
Pietro Fezzardi