code: def filter_by_program(self, prg, opFile):
          
          log_1 = open(self.process_file, 'r')
          log_2 = open(self.command_file, 'r')
          log_3 = open(self.result_file, 'r')
          log_4 = open(self.source_file, 'r')
          
          with open(opFile, 'a') as f:
              for line in log_1:
                  if prg in line:
                      f.write('PROCESS, ' + line)
              for line in log_2:
                  if prg in line:
                      f.write('COMMAND, ' + line)
              for line in log_3:
                  if prg in line:
                      f.write('RESULT, ' + line)
              for line in log_4:
                  if prg in line:
                      f.write('SOURCE, ' + line)
                      
          log_1.close()
          log_2.close()
          log_3.close()
          log_4.close()
docs: parse the log files and extract entries from all 
          logfiles to one file per program (program is the 
          2nd to last entry each logfile)