import string
import random


def __random_sentences(num=1, length=80):
    """
    Generate given number of random ASCII sentences with specified length.
    """
    space_cnt = length//15
    letters = string.ascii_letters
    all_chars = letters + string.digits + ',.' + ' '*space_cnt

    sentences = list()
    for i in range(num):
        # Only use a letter at first position
        sentence = ''.join(random.choices(letters, k=1) +
                random.choices(all_chars, k=length-1))
        sentences.append(sentence)
    return sentences