'Parameters
start_session: pd.Timestamp
The first session.
end_session: pd.Timestamp
The last session.
Returns
int: The total number of minutes for the contiguous chunk of sessions.
between start_session and end_session, inclusive.'

def minutes_count_for_sessions_in_range(self, start_session, end_session):

    return int(self._minutes_per_session[start_session:end_session].sum())
