<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def flatten_model(model):
 """Flatten a model to a list of models. This is used to flatten a ``Binder``'ish model down to a list of contained models. """

    yield model
    if isinstance(model, (TranslucentBinder, Binder,)):
        for m in model:
            # yield from flatten_model(m)
            for x in flatten_model(m):
                yield x