_heim_alloc_object
array = _heim_alloc_object(&array_object, sizeof(*array));
dict = _heim_alloc_object(&dict_object, sizeof(*dict));
ar = _heim_alloc_object(&_heim_autorel_object, sizeof(struct heim_auto_release));
_heim_alloc_object(heim_type_t type, size_t size);
n = _heim_alloc_object(&_heim_number_object, sizeof(int));
s = _heim_alloc_object(&_heim_string_object, len + 1);