code: public Expression reference() {
      if (chunk() instanceof VariableDeclaration) {
        return id(((VariableDeclaration) chunk()).varName(), ImmutableSet.of(this));
      } else {
        return dottedIdWithRequires(symbol(), ImmutableSet.of(this));
      }
    }
docs: Returns a code chunk that can act as a reference to the required symbol.