[BUG]: Stratify notebook does not produce non-directed stratification when asked

[dgauldie]

• Scenario:
• Step:
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Describe the issue
A clear and concise description of what the bug is.

When asking the notebook to "Stratify my model by the ages young and old where young and old can become old, but old cannot become young" the resulting code block produces

model = stratify(
template_model=model,
key= "Age",
strata=['young', 'old'],
structure= [['young', 'old']],
directed=True,
cartesian_control=False,
modify_names=True,
concepts_to_stratify=None, #If none given, will stratify all concepts.
params_to_stratify= None, #If none given, will stratify all parameters.
param_renaming_uses_strata_names = True
)

directed should be False

[liunelson]

A similar problem occurs in this issue:
#5286

I think this only requires a tweak to the code generation instructions. TBD.