docs: function buildDateRangeUnits() {
    var methods = {};
    forEach(DURATION_UNITS.split('|'), function(unit, i) {
      var name = unit + 's', mult, fn;
      if (i < 4) {
        fn = function() {
          return rangeEvery(this, unit, true);
        };
      } else {
        mult = MULTIPLIERS[simpleCapitalize(name)];
        fn = function() {
          return trunc((this.end - this.start) / mult);
        };
      }
      methods[name] = fn;
    });
    defineOnPrototype(Range, methods);
  }