static bool isDollarVar(S s) {
  // Possible BREAKING CHANGE (although probably OK): now also accepting $1 etc.
  ret startsWith(s, '$') && l(s) > 1;
  // OLD: ret startsWith(s, '$') && isJavaIdentifierAfter(s, 1);
}

ifclass Symbol
ifdef SymbolWithMasterSymbol
static bool isDollarVar(Symbol s) {
  ret s != null && s.master.dollarVar;
}
endifdef
endif