code: function(start, end) {
  			if (_.isNumber(start) && _.isNumber(end)) {
  				end -= start;
  			}
  			
  			return this.create(start, end);
  		}
docs: <code>Range</code> object factory, the same as <code>this.create()</code>
  but last argument represents end of range, not length
  @returns {Range}