Delete arbitrary waveform from memory raises AttributeError: '_SessionBase' object has no attribute '_clear_arb_waveform'

• Description of issue

When deleting a arbitrary waveform the driver crashes with the error:
AttributeError: '_SessionBase' object has no attribute '_clear_arb_waveform'

My code is:

options = {'simulate': False, 'driver_setup': {'Model': '5433 (2CH)', 'BoardType': 'PXIe', }, }
self.session = nifgen.Session(resource_name=name, options=options)

def start_generation(self, delete_waveform=True):

    self.session._initiate_generation()

    if delete_waveform is True:
        self.session.channels[self.channel].delete_waveform(self.waveform_handle)

self.waveform_handle = 0

If I dont't delete the waveform I get an error:

nifgen.errors.DriverError: -1074118634: You must specify which waveform to generate.

But since : self.session._initiate_generation() doesn't have arguments to select the waveform that I want to initiate... I don't know how to do it.

I load my waveform with:

self.session.channels[channel].arb_sample_rate = self.sample_rate
self.session.channels[channel].output_mode = nifgen.OutputMode.ARB
self.session.channels[channel].trigger_mode = enums.TriggerMode.SINGLE
self.waveform_handle = self.session.create_waveform(waveform_data_array=waveform)

    self.session.streaming_waveform_handle = self.waveform_handle
    self.session.channels[channel].configure_arb_waveform(waveform_handle=self.waveform_handle, gain=1, offset=0)

I don't know how to overwrite and previous handler.