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Refcounting

One of the simplest ways to implement a garbage collector is to use a reference counting algorithm. It goes something like this:

All objects keep track of a reference_count integer.
When that object is referenced, its reference count is incremented.
When an object is garbage collected, the reference count of any object it references is decremented.
When any object's reference count reaches zero, the object is garbage collected.

Assignment

In snekobject.h: add a new integer field named refcount to snek_object_t.
In snekobject.c: complete the _new_snek_object function:
1. Allocate a snek_object_t on the heap using calloc so its memory is zero-initialized.
2. If the allocation fails, return NULL.
3. Set the refcount to 1.
4. Return the pointer to the new object.