code: def _parse_date(date):
          
          result = ''.join(re.findall('\d', date))
          l = len(result)
  
          # User only input month and day, eg 6-1, 6.26, 0626...
          if l in (2, 3, 4):
              year = str(datetime.today().year)
              return year + result
  
          # User input full format date, eg 201661, 2016-6-26, 20160626...
          if l in (6, 7, 8):
              return result
  
          return ''
docs: Parse from the user input `date`.
  
          e.g. current year 2016:
             input 6-26, 626, ... return 2016626
             input 2016-6-26, 2016/6/26, ... retrun 2016626
  
          This fn wouldn't check the date, it only gather the number as a string.