code: def kernel(self):
          
          stop_words = [ y.lower() for y in self.abbreviations.values() + self.filler_words ]
          kernel = ' '.join([ x for x in self.expand().split() if x.lower() not in stop_words ])
  
          # this is a hack to get around the fact that this is the only two-word phrase we want to block
          # amongst our stop words. if we end up with more, we may need a better way to do this
          kernel = re.sub(r'\s*United States', '', kernel)
  
          return kernel
docs: The 'kernel' is an attempt to get at just the most pithy words in the name