fn option_env_expand(
db: &dyn SourceDatabase,
arg_id: MacroCallId,
tt: &TopSubtree,
call_site: Span,
) -> ExpandResult<TopSubtree>fn option_env_expand(
db: &dyn SourceDatabase,
arg_id: MacroCallId,
tt: &TopSubtree,
call_site: Span,
) -> ExpandResult<TopSubtree>