docs: function buildDateUnitMethods() {
  
    defineInstanceSimilar(sugarDate, DateUnits, function(methods, unit, index) {
      var name = unit.name, caps = simpleCapitalize(name);
  
      if (index > DAY_INDEX) {
        forEach(['Last','This','Next'], function(shift) {
          methods['is' + shift + caps] = function(d, localeCode) {
            return compareDate(d, shift + ' ' + name, 0, localeCode, { locale: 'en' });
          };
        });
      }
      if (index > HOURS_INDEX) {
        methods['beginningOf' + caps] = function(d, localeCode) {
          return moveToBeginningOfUnit(d, index, localeCode);
        };
        methods['endOf' + caps] = function(d, localeCode) {
          return moveToEndOfUnit(d, index, localeCode);
        };
      }
  
      methods['add' + caps + 's'] = function(d, num, reset) {
        return advanceDate(d, name, num, reset);
      };
  
      var since = function(date, d, options) {
        return getTimeDistanceForUnit(date, createDate(d, options, true), unit);
      };
      var until = function(date, d, options) {
        return getTimeDistanceForUnit(createDate(d, options, true), date, unit);
      };
  
      methods[name + 'sAgo']   = methods[name + 'sUntil']   = until;
      methods[name + 'sSince'] = methods[name + 'sFromNow'] = since;
  
    });
  
  }