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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 default_params(model, update_dict=None):
 """ Loads and updates default model parameters Parameters model : str The name of a model update_dict : dict A dict to update default parameters Returns params : dict A dictionary of parameters """


    if model in parameters:
        params = parameters[model].copy()
    else:
        params = None

    if update_dict:
        if params is None:
            params = {}
        params.update(update_dict)

    return params