'cvc(i) is TRUE <=> i-2,i-1,i has the form
consonant - vowel - consonant
and also if the second c is not w,x or y. this is used when trying to
restore an e at the end of a short  e.g.
cav(e), lov(e), hop(e), crim(e), but
snow, box, tray.'

def cvc(self, i):

    if ((i < (self.k0 + 2)) or (not self.cons(i)) or self.cons((i - 1)) or (not self.cons((i - 2)))):
        return 0
    ch = self.b[i]
    if ((ch == 'w') or (ch == 'x') or (ch == 'y')):
        return 0
    return 1
