Generates a new word

def _generate(self, size=None):
        "Generates a new word"
        corpus_letters = list(self.vectors.keys())
        current_letter = random.choice(corpus_letters)
        if size is None:
            size = int(random.normalvariate(self.avg, self.std_dev))

        letters = [current_letter]

        for _ in range(size):
            if current_letter not in corpus_letters:
                # current_letter = random.choice(corpus_letters)
                break
            found_letter = self.vectors[current_letter].choose()
            letters.append(found_letter)
            current_letter = found_letter

        return ''.join(letters)