Function resolve_module_code_unit 

pub fn resolve_module_code_unit(
    python: &dyn PythonSource,
    importer: Option<&ProjectFile>,
    module_fq: &str,
) -> Option<CodeUnit>

The module module_fq names, as written in importer.

importer is None for an FQN-level question that no import statement asked – a dotted name looked up on its own has no import root to be resolved against. With an importer the candidates are narrowed by retain_modules_for_importer first, and a specifier the index holds under no name at all falls through to [module_under_source_root].