def scrub_sentence(sentence)
    sentence.split(/([\s]|--)+/).collect {|a| scrub_word(a)}.select {|a| a.length>0}
  end
def scrub_sentence(sentence)
    sentence.split(/([\s]|--)+/).collect {|a| scrub_word(a)}.select {|a| a.length>0}
  end
clean up all words in  a string, returning an array of clean words