def similarity(other)
      overlap = (wordset & other.wordset).size
      total = wordset.size + other.wordset.size
      100.0 * (overlap * 2.0 / total)
    end
def similarity(other)
      overlap = (wordset & other.wordset).size
      total = wordset.size + other.wordset.size
      100.0 * (overlap * 2.0 / total)
    end
Given another license or project file, calculates the similarity
 as a percentage of words in common