code: def format_timestamp(t):
      
      # Timestamp is only valid for 1678 to 2262
      try:
          datetime_str = str(pd.Timestamp(t))
      except OutOfBoundsDatetime:
          datetime_str = str(t)
  
      try:
          date_str, time_str = datetime_str.split()
      except ValueError:
          # catch NaT and others that don't split nicely
          return datetime_str
      else:
          if time_str == '00:00:00':
              return date_str
          else:
              return '{}T{}'.format(date_str, time_str)
docs: Cast given object to a Timestamp and return a nicely formatted string