Returns a tuple of timestamps of the open and close of the session
        represented by the given label.

        Parameters
        ----------
        session_label: pd.Timestamp
            The session whose open and close are desired.

        Returns
        -------
        (Timestamp, Timestamp)
            The open and close for the given session.

def open_and_close_for_session(self, session_label):
        """
        Returns a tuple of timestamps of the open and close of the session
        represented by the given label.

        Parameters
        ----------
        session_label: pd.Timestamp
            The session whose open and close are desired.

        Returns
        -------
        (Timestamp, Timestamp)
            The open and close for the given session.
        """
        sched = self.schedule

        # `market_open` and `market_close` should be timezone aware, but pandas
        # 0.16.1 does not appear to support this:
        # http://pandas.pydata.org/pandas-docs/stable/whatsnew.html#datetime-with-tz  # noqa
        return (
            sched.at[session_label, 'market_open'].tz_localize(UTC),
            sched.at[session_label, 'market_close'].tz_localize(UTC),
        )