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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(self, file_or_filename):
 """ Loads a pickled case. """

        if isinstance(file_or_filename, basestring):
            fname = os.path.basename(file_or_filename)
            logger.info("Unpickling case file [%s]." % fname)

            file = None
            try:
                file = open(file_or_filename, "rb")
            except:
                logger.error("Error opening %s." % fname)
                return None
            finally:
                if file is not None:
                    case = pickle.load(file)
                    file.close()
        else:
            file = file_or_filename
            case = pickle.load(file)

        return case