Function AtAttribute.token
Returns either identifier or templateSingleArgument,
whichever is set, otherwise Token.
TokenStructure!(ubyte,"import dparse.lexer:TokenTriviaFields,TriviaToken; mixin TokenTriviaFields;") token() pure nothrow @nogc scope @safe const;
This is the single token after the @ for @identifier, @5,
@"string literal", etc.
Not set if parens are used, e.g. not set for @("string in parens").