<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def write(self, file_or_filename):
 """ Writes case data as CSV. """

        if isinstance(file_or_filename, basestring):
            file = open(file_or_filename, "wb")
        else:
            file = file_or_filename

        self.writer = csv.writer(file)

        super(CSVWriter, self).write(file)