import random

def noun():
    "Return a random noun"
    n = ['dog', 'cat', 'poodle', 'manx']
    return random.choice(n)

def det():
    "Return a random determiner"
    return random.choice(['a', 'the'])

def adj():
    "Return a random adjective"
    return random.choice(['sad', 'happy', 'silly'])

def verb():
    "Return a transitive verb"
    return random.choice(['likes', 'saw'])

def np():
    "Returns a random noun phrase"
    return det() + ' ' + adj() + ' ' + noun()

def vp():
    "Returns a random verb phrase"
    return verb() +  ' ' + np()

def s():
    "Return a simple sentence"
    return np().capitalize() + ' ' + vp() + '.'