function baseWhile(array, predicate, isDrop, fromRight) {
	      var length = array.length,
	          index = fromRight ? length : -1;

	      while ((fromRight ? index-- : ++index < length) && predicate(array[index], index, array)) {}
	      return isDrop
	        ? baseSlice(array, (fromRight ? 0 : index), (fromRight ? index + 1 : length))
	        : baseSlice(array, (fromRight ? index + 1 : 0), (fromRight ? length : index));
	    }
The base implementation of `_.dropRightWhile`, `_.dropWhile`, `_.takeRightWhile`,
and `_.takeWhile` without support for callback shorthands and `this` binding.

@private
@param {Array} array The array to query.
@param {Function} predicate The function invoked per iteration.
@param {boolean} [isDrop] Specify dropping elements instead of taking them.
@param {boolean} [fromRight] Specify iterating from right to left.
@returns {Array} Returns the slice of `array`.