input: def primeSieve(n: int) -> List[int]:
      """Returns a list of all prime numbers up to a given number n using the Sieve of Eratosthenes algorithm.
      >>> primeSieve(10)
      [2, 3, 5, 7]
      >>> primeSieve(20)
      [2, 3, 5, 7, 11, 13, 17, 19]
      """
      prime_list = [True for i in range(n+1)]
      p = 2
      while (p * p <= n):
          if (prime_list[p] == True):
              for i in range(p * 2, n+1, p):
                  prime_list[i] = False
          p += 1
      primes = []
      for p in range(2, n):
          if prime_list[p]:
              primes.append(p)
      return primes
output:     prime_list = [True for i in range(n+1)]
      p = 2
      while (p * p <= n):
          if (prime_list[p] == True):
              for i in range(p * 2, n+1, p):
                  prime_list[i] = False
          p += 1
      primes = []
      for p in range(2, n):
          if prime_list[p]:
              primes.append(p)
      return primes