'Generate a random sentence
:example \'Lorem ipsum dolor sit amet.\'
:param nb_words: around how many words the sentence should contain
:param variable_nb_words: set to false if you want exactly ``nb``
words returned, otherwise the result may include a number of words
of ``nb`` +/-40% (with a minimum of 1)
:param ext_word_list: a list of words you would like to have instead of
\'Lorem ipsum\'.
:rtype: str'

@classmethod
def sentence(cls, nb_words=6, variable_nb_words=True, ext_word_list=None):

    if (nb_words <= 0):
        return ''
    if variable_nb_words:
        nb_words = cls.randomize_nb_elements(nb_words)
    words = cls.words(nb=nb_words, ext_word_list=ext_word_list)
    words[0] = words[0].title()
    return (cls.word_connector.join(words) + cls.sentence_punctuation)
