/**
  * Stem a singular word to its common stem form.
  *
  * @param  string $word the word to stem, e.g : mengalahkan
  * @return string common stem form, e.g : kalah
  */
 protected function stemSingularWord($word)
 {
     $context = new Context($word, $this->dictionary, $this->visitorProvider);
     $context->execute();
     return $context->getResult();
 }