tokensArg property
The child's tokens formal, when this instance receives the parent's
set — the file spells PromoBadgeArgs(label: title, tokens: tokens),
and the name is the child's own for its formal. Null when the child
declares none, or the parent has no set to hand down. Threaded by the
tool whenever both sides have a formal, never by the author.
Implementation
String? tokensArg;