function recursiveSearch(aLow, aHigh, aNeedle, aHaystack, aCompare, aBias) {
	  // This function terminates when one of the following is true:
	  //
	  //   1. We find the exact element we are looking for.
	  //
	  //   2. We did not find the exact element, but we can return the index of
	  //      the next-closest element.
	  //
	  //   3. We did not find the exact element, and there is no next-closest
	  //      element than the one we are searching for, so we return -1.
	  var mid = Math.floor((aHigh - aLow) / 2) + aLow;
	  var cmp = aCompare(aNeedle, aHaystack[mid], true);
	  if (cmp === 0) {
	    // Found the element we are looking for.
	    return mid;
	  }
	  else if (cmp > 0) {
	    // Our needle is greater than aHaystack[mid].
	    if (aHigh - mid > 1) {
	      // The element is in the upper half.
	      return recursiveSearch(mid, aHigh, aNeedle, aHaystack, aCompare, aBias);
	    }

	    // The exact needle element was not found in this haystack. Determine if
	    // we are in termination case (3) or (2) and return the appropriate thing.
	    if (aBias == exports.LEAST_UPPER_BOUND) {
	      return aHigh < aHaystack.length ? aHigh : -1;
	    } else {
	      return mid;
	    }
	  }
	  else {
	    // Our needle is less than aHaystack[mid].
	    if (mid - aLow > 1) {
	      // The element is in the lower half.
	      return recursiveSearch(aLow, mid, aNeedle, aHaystack, aCompare, aBias);
	    }

	    // we are in termination case (3) or (2) and return the appropriate thing.
	    if (aBias == exports.LEAST_UPPER_BOUND) {
	      return mid;
	    } else {
	      return aLow < 0 ? -1 : aLow;
	    }
	  }
	}
Recursive implementation of binary search.

@param aLow Indices here and lower do not contain the needle.
@param aHigh Indices here and higher do not contain the needle.
@param aNeedle The element being searched for.
@param aHaystack The non-empty array being searched.
@param aCompare Function which takes two elements and returns -1, 0, or 1.
@param aBias Either 'binarySearch.GREATEST_LOWER_BOUND' or
    'binarySearch.LEAST_UPPER_BOUND'. Specifies whether to return the
    closest element that is smaller than or greater than the one we are
    searching for, respectively, if the exact element cannot be found.