refine select()/collect() on Singleton
refine select()/collect() on Singleton

lucaswerkmeister/ceylon.language,ceylon/ceylon.language,jvasileff/ceylon.language,unratito/ceylon.language,ceylon/ceylon.language,lucaswerkmeister/ceylon.language,jvasileff/ceylon.language,unratito/ceylon.language