'Return the region RV that is used by the French stemmer.
If the word begins with two vowels, RV is the region after
the third letter. Otherwise, it is the region after the first
vowel not at the beginning of the word, or the end of the word
if these positions cannot be found. (Exceptionally, u\'par\',
u\'col\' or u\'tap\' at the beginning of a word is also taken to
define RV as the region to their right.)
:param word: The French word whose region RV is determined.
:type word: str or unicode
:param vowels: The French vowels that are used to determine
the region RV.
:type vowels: unicode
:return: the region RV for the respective French word.
:rtype: unicode
:note: This helper method is invoked by the stem method of
the subclass FrenchStemmer. It is not to be invoked directly!'

def __rv_french(self, word, vowels):

    rv = u''
    if (len(word) >= 2):
        if (word.startswith((u'par', u'col', u'tap')) or ((word[0] in vowels) and (word[1] in vowels))):
            rv = word[3:]
        else:
            for i in range(1, len(word)):
                if (word[i] in vowels):
                    rv = word[(i + 1):]
                    break
    return rv
