ERROR setting MG energy-edge

Hi everyone,

i am trying to create a MG Cross section data library using OpenMC. I defined the Materials, geometry and setting and was able to Plot my designed Model.

after this step :

settings_file.trigger_active = True
settings_file.trigger_max_batches = settings_file.batches * 4
settings_file.export_to_xml()

I want to define a 56-group structure using the built-in EnergyGroups class and I get this error:

Traceback (most recent call last):
File “mg.py”, line 106, in
groups = mgxs.EnergyGroups()
TypeError: init() missing 1 required positional argument: ‘group_edges’

can anyone help me with this error?
BTW I am using OpenMC v: v0.13.3

Thank you in Advance
Mary