import random
import itertools


def main():
    def_len = 4
    nucleotyde_set = [''.join(i) for i in itertools.combinations_with_replacement('ACGT', 3)]
    nucleotyde_chain = [random.choice(nucleotyde_set) for i in range(def_len)]
    random.seed(hash(''.join(nucleotyde_chain)))
    if random.randint(0, 10) % 2 == 0:
        del nucleotyde_chain[random.randint(0, len(nucleotyde_chain) - 1)]
    else:
        nucleotyde_chain.append(nucleotyde_set[random.randint(0, len(nucleotyde_set) - 1)])

    source = ["import random", "import itertools", "\n", "def main():", "    def_len = 4", "    nucleotyde_set = [''.join(i) for i in itertools.combinations_with_replacement('ACGT', 3)]", "    nucleotyde_chain = %s", "    random.seed(hash(''.join(nucleotyde_chain)))", "    if random.randint(0, 10) % 2 == 0:", "        del nucleotyde_chain[random.randint(0, len(nucleotyde_chain) - 1)]", "    else:", "        nucleotyde_chain.append(nucleotyde_set[random.randint(0, len(nucleotyde_set) - 1)])", "    source = %s", "    for i in range(0, 6):", "        print(source[i])", "    print(source[6] % nucleotyde_chain)", "    for i in range(7, 12):", "        print(source[i])", "    print(source[12] % source)", "    for i in range(13, len(source)):", "        print(source[i])", "\n", "if __name__ == '__main__':", "    main()"]

    for i in range(0, 6):
        print(source[i])
    print(source[6] % nucleotyde_chain)
    for i in range(7, 12):
        print(source[i])
    print(source[12] % source)
    for i in range(13, len(source)):
        print(source[i])


if __name__ == '__main__':
    main()

Traceback (most recent call last):
  Line 28, in <module>
    main()
  Line 7, in main
    nucleotyde_set = [''.join(i) for i in itertools.combinations_with_replacement('ACGT', 3)]
AttributeError: 'module' object has no attribute 'combinations_with_replacement'