Internal helper to retrieve global option value. If the option is NULL (not set), returns the provided default. If a non-NULL value is explicitly passed (from a method call), that takes priority over the global option.
.get_option(name, default = NULL, override = NULL)The effective value to use
Option name ("paral", "block_size", "threads", or "compression")
Fallback value if option is NULL
Value passed to method call (takes priority if not NULL/missing)