+R's object tracking differs from Python as it does not involve
+reference counting. It is using at attribute NAMED (more on this below),
+and a list of objects to be `preserved` (from garbage collection).
+Rpy2 is using its own reference counting system in order to bridge R with
+Python and keep the pass-by-reference approach familiar to Python users.
+At the time of writting, the implementation of R is such as
+adding an item to the list of preserved objects is of constant time-complexity
+while removing an item from the list of preserved object is linear in the
+number of objects already preserved.
Whenever the pass-by-value paradigm is applied stricly,
garbage collection is straightforward as objects only live within
the scope they are declared, but R is using a slight modification