A pointer to a function:
given a pointer
.I p
-to at least
-.I initsz
-bytes of appropriately aligned memory,
-initialize an instance of the class in it:
-all of the vtable and class pointers are initialized,
-as are slots for which initializers are defined.
+to an imprinted instance,
+initialize all of its slots for which initializers are defined.
Other slots are left untouched.
The function returns its argument
.IR p .