code: function(comparator, nullsFirst)
    {
      var cmp = comparator ? createComparator( comparator, nullsFirst ) : this.comparator;
  
      return isSorted( cmp, this );
    }
docs: Determines if the collection is currently sorted based on the current
  comparator of the collection unless a comparator is given
  
  @method
  @memberof Rekord.Collection#
  @param {ComparatorInput} [comparator] -
  The comparator input to convert to a comparison function.
  @param {Boolean} [nullsFirst=false] -
  When a comparison is done involving a null/undefined value this can
  determine which is ordered before the other.
  @see Rekord.createComparator
  @return {Boolean}