old_contents: import logging
  
  def start_logger(output=None, verbose=0):
      """
      Start an instance of Logger for logging
  
      output : `str`
          output directory (./)
  
      verbose: `int`
          Verbosity, 0=CRITICAL, 1=WARNING, 2=INFO, 3=DEBUG
  
      fmt: `str`
          format for logger (None) See logging documentation for details
  
      """
      # possible levels
      verbose = min(verbose, 3)
      # levels 0, 1, 2, 3
      levels = ['CRITICAL', 'WARNING', 'INFO', 'DEBUG']
      level = levels[verbose]
      fmt = '%(asctime)s - %(name)-8s: %(message)s'
      # setup logger
      logger = logging.getLogger('CPNest')
      logger.setLevel(level)
      # handle command line output
      ch = logging.StreamHandler()
      ch.setFormatter(logging.Formatter(fmt, datefmt='%Y-%m-%d, %H:%M:%S'))
      logger.addHandler(ch)
  
      if output is not None:
          # log to file
          fh = logging.FileHandler(output + 'cpnest.log')
          fh.setFormatter(logging.Formatter(fmt))
          logger.addHandler(fh)
      print(logger.critical('Logging level: {}'.format(level)))
      return logger
  
new_contents: import logging
  
  def start_logger(output=None, verbose=0):
      """
      Start an instance of Logger for logging
  
      output : `str`
          output directory (./)
  
      verbose: `int`
          Verbosity, 0=CRITICAL, 1=WARNING, 2=INFO, 3=DEBUG
  
      fmt: `str`
          format for logger (None) See logging documentation for details
  
      """
      # possible levels
      verbose = min(verbose, 3)
      # levels 0, 1, 2, 3
      levels = ['CRITICAL', 'WARNING', 'INFO', 'DEBUG']
      level = levels[verbose]
      fmt = '%(asctime)s - %(name)-8s: %(message)s'
      # setup logger
      logger = logging.getLogger('CPNest')
      logger.setLevel(level)
      # handle command line output
      ch = logging.StreamHandler()
      ch.setFormatter(logging.Formatter(fmt, datefmt='%Y-%m-%d, %H:%M:%S'))
      logger.addHandler(ch)
  
      if output is not None:
          # log to file
          fh = logging.FileHandler(output + 'cpnest.log')
          fh.setFormatter(logging.Formatter(fmt, datefmt='%Y-%m-%d, %H:%M:%S'))
          logger.addHandler(fh)
      print(logger.critical('Logging level: {}'.format(level)))
      return logger
  
subject: Fix format of log file