code: function(offset) {
  			var monthNum = this.month	
  
  			offset = offset || 0
  
  			monthNum += offset
  
  			if(monthNum < 0) { monthNum = 11 }
  			if(monthNum > 11) { monthNum = monthNum - 12 }
  
  			return monthNum
  		}
docs: Returns the month based on offset
  (Months after index of 11 return 0)
  @param integer month offset