code: def session_distance(self, start_session_label, end_session_label):
          
          negate = end_session_label < start_session_label
          if negate:
              start_session_label, end_session_label = (
                  end_session_label,
                  start_session_label,
              )
          start_idx = self.all_sessions.searchsorted(start_session_label)
          end_idx = self.all_sessions.searchsorted(
              end_session_label,
              side='right',
          )
  
          out = end_idx - start_idx
          if negate:
              out = -out
  
          return out
docs: Given a start and end session label, returns the distance between them.
          For example, for three consecutive sessions Mon., Tues., and Wed,
          ``session_distance(Mon, Wed)`` returns 3. If ``start_session`` is after
          ``end_session``, the value will be negated.
  
          Parameters
          ----------
          start_session_label: pd.Timestamp
              The label of the start session.
          end_session_label: pd.Timestamp
              The label of the ending session inclusive.
  
          Returns
          -------
          int
              The distance between the two sessions.