code: def to_datetime(arg):
      
  
  
      if isinstance(arg, datetime.datetime):
          return arg
      elif arg == 0:
          return datetime.datetime.now()
      elif isinstance(arg, str):
          if arg == "now":
              arg = datetime.datetime.now()
          elif arg == "?":
              arg = datetime.datetime(1970, 1, 1)
          else:
              arg = str2dt(arg)
      elif isinstance(arg, datetime.date):
          arg = date2datetime(arg)
      elif isinstance(arg, (int, float)):
          # Suppose it is a timestamp
          arg = ts2dt(arg)
      else:
          raise TypeError("Wrong type for argument 'arg': {}".format(arg.__class__.__name__))
  
      return arg
docs: Tries to convert any type of argument to datetime
  
      Args:
          arg: datetime, date, or str. If "?", will be converted to 1970-1-1.
               if 0 or "now", will be converted to datetime.datetime.now()