* Each "alloc" function allocates and returns a new instance of the respective
* data structure. The "alloc" function is not given any information about the
* use of the new data structure, so it cannot perform much initialization.
* Each "alloc" function allocates and returns a new instance of the respective
* data structure. The "alloc" function is not given any information about the
* use of the new data structure, so it cannot perform much initialization.