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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def read_data(self, chan=None, begtime=None, endtime=None, begsam=None, endsam=None, s_freq=None):
 """Read the data and creates a ChanTime instance Parameters chan : list of strings names of the channels to read begtime : int or datedelta or datetime or list start of the data to read; if it's int or float, it's assumed it's s; if it's timedelta, it's assumed from the start of the recording; if it's datetime, it's assumed it's absolute time. It can also be a list of any of the above type. endtime : int or datedelta or datetime end of the data to read; if it's int or float, it's assumed it's s; if it's timedelta, it's assumed from the start of the recording; if it's datetime, it's assumed it's absolute time. It can also be a list of any of the above type. begsam : int first sample (this sample will be included) endsam : int last sample (this sample will NOT be included) s_freq : int sampling frequency of the data Returns ------- An instance of ChanTime Notes ----- begsam and endsam follow Python convention, which starts at zero, includes begsam but DOES NOT include endsam. If begtime and endtime are a list, they both need the exact same length and the data will be stored in trials. If neither begtime or begsam are specified, it starts from the first sample. If neither endtime or endsam are specified, it reads until the end. """

        data = ChanTime()
        data.start_time = self.header['start_time']
        data.s_freq = s_freq = s_freq if s_freq else self.header['s_freq']

        if chan is None:
            chan = self.header['chan_name']
        if not (isinstance(chan, list) or isinstance(chan, tuple)):
            raise TypeError('Parameter "chan" should be a list')
        add_ref = False
        if '_REF' in chan:
            add_ref = True
            chan[:] = [x for x in chan if x != '_REF']
        idx_chan = [self.header['chan_name'].index(x) for x in chan]

        if begtime is None and begsam is None:
            begsam = 0
        if endtime is None and endsam is None:
            endsam = self.header['n_samples']

        if begtime is not None:
            if not isinstance(begtime, list):
                begtime = [begtime]
            begsam = []
            for one_begtime in begtime:
                begsam.append(_convert_time_to_sample(one_begtime, self))
        if endtime is not None:
            if not isinstance(endtime, list):
                endtime = [endtime]
            endsam = []
            for one_endtime in endtime:
                endsam.append(_convert_time_to_sample(one_endtime, self))

        if not isinstance(begsam, list):
            begsam = [begsam]
        if not isinstance(endsam, list):
            endsam = [endsam]

        if len(begsam) != len(endsam):
            raise ValueError('There should be the same number of start and ' +
                             'end point')
        n_trl = len(begsam)

        data.axis['chan'] = empty(n_trl, dtype='O')
        data.axis['time'] = empty(n_trl, dtype='O')
        data.data = empty(n_trl, dtype='O')

        for i, one_begsam, one_endsam in zip(range(n_trl), begsam, endsam):            
            dataset = self.dataset
            lg.debug('begsam {0: 6}, endsam {1: 6}'.format(one_begsam,
                     one_endsam))
            dat = dataset.return_dat(idx_chan, one_begsam, one_endsam)
            chan_in_dat = chan
            
            if add_ref:
                zero_ref = zeros((1, one_endsam - one_begsam))
                dat = concatenate((dat, zero_ref), axis=0)
                chan_in_dat.append('_REF')
            
            data.data[i] = dat
            data.axis['chan'][i] = asarray(chan_in_dat, dtype='U')
            data.axis['time'][i] = (arange(one_begsam, one_endsam) / s_freq)

        return data