fn add_1(x int, y int) int
add_1 is exported with the C name
add_1. It can be called by external programs, when the module is compiled as a shared library. It is exported, because the function is declared as public with
pub. The exported C name is
add_1, because of the export: tag. (Normally, the exported name is a V mangled version based on the module name followed by __, followed by the fn name, i.e. it would have been
library__add_1, if not for the export: tag).