code: def isoformat(self, sep='T'):
          
  
          if self.microsecond == 0:
              return self.strftime('0000-%%m-%%d%s%%H:%%M:%%S' % sep)
          return self.strftime('0000-%%m-%%d%s%%H:%%M:%%S.%%f' % sep)
docs: Formats the date as "%Y-%m-%d %H:%M:%S" with the sep param between the
          date and time portions
  
          :param set:
              A single character of the separator to place between the date and
              time
  
          :return:
              The formatted datetime as a unicode string in Python 3 and a byte
              string in Python 2