lookup ~version name retrieves or instantiates a host function by the given name.

Used to plug host function wrappers in the WASN interpreter linker.

lookup_opt ~version name is exactly lookup name but returns an option instead of raising `Not_found`.

registry ~version ~write_debug returns the host functions registry for the expected PVM version, and with the expected implementation for the write_debug function.

A durable key was given by the kernel with a longer-than-allowed length.

Defines the tick consumption of memory access for the host functions.