How to use the pyedflib._extensions._pyedflib.FILETYPE_BDFPLUS function in pyEDFlib

self.patient_code = ''
        self.technician = ''
        self.equipment = ''
        self.recording_additional = ''
        self.patient_additional = ''
        self.admincode = ''
        self.gender = None
        self.recording_start_time = datetime.now()
        self.birthdate = ''
        self.duration = 1
        self.number_of_annotations = 1 if file_type in [FILETYPE_EDFPLUS, FILETYPE_BDFPLUS] else 0
        self.n_channels = n_channels
        self.channels = []
        self.sample_buffer = []
        for i in np.arange(self.n_channels):
            if self.file_type == FILETYPE_BDFPLUS or self.file_type == FILETYPE_BDF:
                self.channels.append({'label': 'test_label', 'dimension': 'mV', 'sample_rate': 100,
                                      'physical_max': 1.0, 'physical_min': -1.0,
                                      'digital_max': 8388607,'digital_min': -8388608,
                                      'prefilter': 'pre1', 'transducer': 'trans1'})
            elif self.file_type == FILETYPE_EDFPLUS or self.file_type == FILETYPE_EDF:
                self.channels.append({'label': 'test_label', 'dimension': 'mV', 'sample_rate': 100,
                                      'physical_max': 1.0, 'physical_min': -1.0,
                                      'digital_max': 32767, 'digital_min': -32768,
                                      'prefilter': 'pre1', 'transducer': 'trans1'})

                self.sample_buffer.append([])
        self.handle = open_file_writeonly(self.path, self.file_type, self.n_channels)
        if (self.handle < 0):
            raise IOError(write_errors[self.handle])