code: def _has_vowel(self, term):
          
          for letter in term:
              if letter in self._vowels:
                  return True
          return False
docs: Return Porter helper function _has_vowel value.
  
          Parameters
          ----------
          term : str
              The word to scan for vowels
  
          Returns
          -------
          bool
              True iff a vowel exists in the term (as defined in the Porter
              stemmer definition)