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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 calculate_median(given_list):
 """ Returns the median of values in the given list. """

        median = None

        if not given_list:
            return median

        given_list = sorted(given_list)
        list_length = len(given_list)

        if list_length % 2:
            median = given_list[int(list_length / 2)]
        else:
            median = (given_list[int(list_length / 2)] + given_list[int(list_length / 2) - 1]) / 2.0

        return median