new_contents: """ Project Euler problem #10. """
  
  import math as mt
  
  
  def problem():
      """ Solve the problem.
  
      The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
      Find the sum of all the primes below two million.
  
      Answer: 142913828922
  
      """
      return sum(prime_numbers(2000000))
  
  
  def prime_numbers(_max):
      """ Get prime numbers below passed max. """
      a = [True] * _max
      for n in range(2, int(mt.sqrt(_max)) + 1):
          if not a[n]:
              continue
          for j in range(n ** 2, _max, n):
              a[j] = False
      return [n for n in range(2, _max) if a[n]]
  
  
  if __name__ == '__main__':
      print problem()
  
subject: Solve 10.