fn include(vm: &mut VM, self_val: Value, _args: &Args2) -> VMResult {
    for arg in vm.args().to_owned() {
        let module = arg.expect_module("arg")?;
        self_val
            .into_module()
            .append_include(&mut vm.globals, module);
    }
    Ok(self_val)
}
Module#include(*modules) -> self
https://docs.ruby-lang.org/ja/latest/method/Module/i/include.html
ruruby/src/builtin/module.rs