code: def write_case_data(self, file):
          
          change_code = 0
          s_base = self.case.base_mva
          timestr = time.strftime("%Y%m%d%H%M", time.gmtime())
          file.write("%d, %8.2f, 30 / PSS(tm)E-30 RAW created by Pylon (%s).\n" %
                     (change_code, s_base, timestr))
          file.write("Modified by Hantao Cui, CURENT, UTK\n ")
          file.write("%s, %d BUSES, %d BRANCHES\n" %
                     (self.case.name, len(self.case.buses), len(self.case.branches)))
docs: Writes case data to file.