code: def transform_backend_kwargs(kwargs):
      kwargs["n"] = kwargs["observed"].sum(axis=1).astype(int)
      return kwargs
  
imports: import numpy
  import pytensor.tensor
  import xarray
  from bambi.families.family import Family
  from bambi.transformations import transformations_namespace
  from bambi.utils import extract_argument_names, get_aliased_name
label_desc: Use image node_id 6 for calling the Multinomial obj's underlying member method code with example usage: obj.transform_backend_kwargs(kwargs) and returns: kwargs