input: Write a function to find the largest prime factor of a given number. If the number is prime, return the number itself.
  def largest_prime_factor(n):
      factors = []
      for i in range(2, int(math.sqrt(n)) + 1):
          if n % i == 0:
              factors.append(i)
              factors.append(int(n / i))
      prime_factors = []
      for potential_factor in factors:
          is_prime = True
          for j in range(2, int(math.sqrt(potential_factor)) + 1):
              if potential_factor % j == 0 and potential_factor != j:
                  is_prime = False
          if is_prime:
              prime_factors.append(potential_factor)
      if prime_factors:
          return max(prime_factors)
      return n
  
  assert largest_prime_factor(331) == 331
  assert largest_prime_factor(14) == 7
  assert largest_prime_factor(15) == 5
  assert largest_prime_factor(18) == 3
  assert largest_prime_factor(1) == 1
output: def largest_prime_factor(n):
      factors = []
      for i in range(2, int(math.sqrt(n)) + 1):
          if n % i == 0:
              factors.append(i)
              factors.append(int(n / i))
      prime_factors = []
      for potential_factor in factors:
          is_prime = True
          for j in range(2, int(math.sqrt(potential_factor)) + 1):
              if potential_factor % j == 0 and potential_factor != j:
                  is_prime = False
          if is_prime:
              prime_factors.append(potential_factor)
      if prime_factors:
          return max(prime_factors)
      return n