import random, string

def rand_str(min_len=5, max_len=10, charset=None):
    if charset is None:
        charset = string.ascii_letters + string.digits
    length = random.randint(min_len, max_len)
    return ''.join(random.choice(charset) for _ in range(length))

def rand_var(min_len=6, max_len=12):
    first = random.choice(string.ascii_letters)
    rest = ''.join(random.choice(string.ascii_letters + string.digits) for _ in range(random.randint(min_len-1, max_len-1)))
    return first + rest

def rand_label(min_len=5, max_len=10):
    chars = string.ascii_letters + string.digits + '[]{}()_'
    first = random.choice(string.ascii_letters)
    rest = ''.join(random.choice(chars) for _ in range(random.randint(min_len-1, max_len-1)))
    return first + rest

def rand_word():
    vowels = 'aeiou'
    consonants = 'bcdfghjklmnpqrstvwxyz'
    length = random.randint(3, 12)
    word = ''
    for i in range(length):
        word += random.choice(consonants) if i % 2 == 0 else random.choice(vowels)
    return word

def rand_words(min_count=3, max_count=10):
    return ' '.join(rand_word() for _ in range(random.randint(min_count, max_count)))

def rand_case(s):
    return ''.join(c.upper() if random.random() > 0.5 else c.lower() for c in s)