code: static int hash(int n) {
  		int hash = 5381;
  		hash = ((hash << 5) + hash) + (n & 0xFF); /* hash * 33 + c */
  		hash = ((hash << 5) + hash) + ((n >> 8) & 0xFF);
  		hash = ((hash << 5) + hash) + ((n >> 16) & 0xFF);
  		hash = ((hash << 5) + hash) + ((n >> 24) & 0xFF);
  		hash &= 0x7FFFFFFF;
  		return hash;
  	}
docs: makes a hash out of an int