code: def next_session_label(self, session_label):
          
          idx = self.schedule.index.get_loc(session_label)
          try:
              return self.schedule.index[idx + 1]
          except IndexError:
              if idx == len(self.schedule.index) - 1:
                  raise ValueError("There is no next session as this is the end"
                                   " of the exchange calendar.")
              else:
                  raise
docs: Given a session label, returns the label of the next session.
  
          Parameters
          ----------
          session_label: pd.Timestamp
              A session whose next session is desired.
  
          Returns
          -------
          pd.Timestamp
              The next session label (midnight UTC).
  
          Notes
          -----
          Raises ValueError if the given session is the last session in this
          calendar.