code: def minute_to_session_label(self, dt, direction="next"):
          
          if direction == "next":
              try:
                  return self._minute_to_session_label_cache[dt]
              except KeyError:
                  pass
  
          idx = searchsorted(self.market_closes_nanos, dt)
          current_or_next_session = self.schedule.index[idx]
          self._minute_to_session_label_cache[dt] = current_or_next_session
  
          if direction == "next":
              return current_or_next_session
          elif direction == "previous":
              if not is_open(self.market_opens_nanos, self.market_closes_nanos,
                             dt):
                  # if the exchange is closed, use the previous session
                  return self.schedule.index[idx - 1]
          elif direction == "none":
              if not is_open(self.market_opens_nanos, self.market_closes_nanos,
                             dt):
                  # if the exchange is closed, blow up
                  raise ValueError("The given dt is not an exchange minute!")
          else:
              # invalid direction
              raise ValueError("Invalid direction parameter: "
                               "{0}".format(direction))
  
          return current_or_next_session
docs: Given a minute, get the label of its containing session.
  
          Parameters
          ----------
          dt : pd.Timestamp or nanosecond offset
              The dt for which to get the containing session.
  
          direction: str
              "next" (default) means that if the given dt is not part of a
              session, return the label of the next session.
  
              "previous" means that if the given dt is not part of a session,
              return the label of the previous session.
  
              "none" means that a KeyError will be raised if the given
              dt is not part of a session.
  
          Returns
          -------
          pd.Timestamp (midnight UTC)
              The label of the containing session.