code: def _number_of_set_bits(x):
      '''
      Returns the number of bits that are set in a 32bit int
      '''
      # Taken from http://stackoverflow.com/a/4912729. Many thanks!
      x -= (x >> 1) & 0x55555555
      x = ((x >> 2) & 0x33333333) + (x & 0x33333333)
      x = ((x >> 4) + x) & 0x0f0f0f0f
      x += x >> 8
      x += x >> 16
      return x & 0x0000003f _number_of_set_bits(x):
      '''
      Returns the number of bits that are set in a 32bit int
      '''
      # Taken from http://stackoverflow.com/a/4912729. Many thanks!
      x -= (x >> 1) & 0x55555555
      x = ((x >> 2) & 0x33333333) + (x & 0x33333333)
      x = ((x >> 4) + x) & 0x0f0f0f0f
      x += x >> 8
      x += x >> 16
      return x & 0x0000003f
docs: Returns the number of bits that are set in a 32bit int