new_contents: # Time:  O(log(R - L)) = O(1)
  # Space: O(1)
  
  class Solution(object):
      def countPrimeSetBits(self, L, R):
          """
          :type L: int
          :type R: int
          :rtype: int
          """
          def bitCount(n):
              result = 0
              while n:
                  n &= n-1
                  result += 1
              return result
          
          primes = {2, 3, 5, 7, 11, 13, 17, 19}
          return sum(bitCount(i) in primes
                     for i in xrange(L, R+1))
  
subject: Create prime-number-of-set-bits-in-binary-representation.py