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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 read_vensim(mdl_file):
 """ Construct a model from Vensim `.mdl` file. Parameters mdl_file : <string> The relative path filename for a raw Vensim `.mdl` file Returns ------- model: a PySD class object Elements from the python model are loaded into the PySD class and ready to run Examples -------- """


    from .py_backend.vensim.vensim2py import translate_vensim
    from .py_backend import functions
    py_model_file = translate_vensim(mdl_file)
    model = functions.Model(py_model_file)
    model.mdl_file = mdl_file
    return model