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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def build_model_classes(metadata):

 """Generate a model class for any models contained in the specified spec file."""

    i = importlib.import_module(metadata)
    env = get_jinja_env()
    model_template = env.get_template('model.py.jinja2')
    for model in i.models:
        with open(model_path(model.name.lower()), 'w') as t:
            t.write(model_template.render(model_md=model))