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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 make_value_from_env(self, param, value_type, function):
 """ get environment variable """

        value = os.getenv(param)
        if value is None:
            self.notify_user("Environment variable `%s` undefined" % param)
        return self.value_convert(value, value_type)