Usage
{{Infobox language/codelist|code=abc}}→abc{{Infobox language/codelist|abc}}→abc{{Infobox language/codelist|abc|def}}→abc– def{{Infobox language/codelist}}→ (blank returns blank)
{{Infobox language/codelist|code=abc}} → abc{{Infobox language/codelist|abc}} → abc{{Infobox language/codelist|abc|def}} → abc – def{{Infobox language/codelist}} → (blank returns blank)