code: def rwh_primes1(n):
      # http://stackoverflow.com/questions/2068372/fastest-way-to-list-all-primes-below-n-in-python/3035188#3035188
      ''' Returns  a list of primes < n '''
      sieve = [True] * (n/2)
      for i in xrange(3,int(n**0.5)+1,2):
          if sieve[i/2]:
              sieve[i*i/2::i] = [False] * ((n-i*i-1)/(2*i)+1)
      return [2] + [2*i+1 for i in xrange(1,n/2) if sieve[i]f rwh_primes1(n):
      # http://stackoverflow.com/questions/2068372/fastest-way-to-list-all-primes-below-n-in-python/3035188#3035188
      ''' Returns  a list of primes < n '''
      sieve = [True] * (n/2)
      for i in xrange(3,int(n**0.5)+1,2):
          if sieve[i/2]:
              sieve[i*i/2::i] = [False] * ((n-i*i-1)/(2*i)+1)
      return [2] + [2*i+1 for i in xrange(1,n/2) if sieve[i]]
docs: Returns  a list of primes < n