# Returns the number of bits of specified value (0 or 1) in `self`
	#
	#	 assert 10.number_bits(1) == 2
	#	 assert 10.number_bits(0) == 30
	fun number_bits(value: Int): Int `{
		assert(value == 0 || value == 1);

		long int bound = 1L << 31;
		int count = 0;
		long int i;

		if(value == 1)
		{
			for(i=bound; i>0; i/=2)
			{
				if(self & i)
					count++;
			}
		}
		else
		{
			for(i=bound; i>0; i/=2)
			{
				if(!(self & i))
					count++;
			}
		}
		return count;
	`}