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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 get_period(date_from: date, date_to: date) -> str: """ Returns the period string from the given dates """

    assert isinstance(date_from, date)
    assert isinstance(date_to, date)

    str_from: str = date_from.isoformat()
    str_to: str = date_to.isoformat()

    return str_from + " - " + str_to