code: def define_logging_options(options=None):
      """Add logging-related flags to ``options``.
  
      These options are present automatically on the default options instance;
      this method is only necessary if you have created your own `.OptionParser`.
  
      .. versionadded:: 4.2
          This function existed in prior versions but was broken and undocumented until 4.2.
      """
      if options is None:
          # late import to prevent cycle
          import tornado.options
  
          options = tornado.options.options
      options.define(
          "logging",
          default="info",
          help=(
              "Set the Python log level. If 'none', tornado won't touch the "
              "logging configuration."
          ),
          metavar="debug|info|warning|error|none",
      )
      options.define(
          "log_to_stderr",
          type=bool,
          default=None,
          help=(
              "Send log output to stderr (colorized if possible). "
              "By default use stderr if --log_file_prefix is not set and "
              "no other logging is configured."
          ),
      )
      options.define(
          "log_file_prefix",
          type=str,
          default=None,
          metavar="PATH",
          help=(
              "Path prefix for log files. "
              "Note that if you are running multiple tornado processes, "
              "log_file_prefix must be different for each of them (e.g. "
              "include the port number)"
          ),
      )
      options.define(
          "log_file_max_size",
          type=int,
          default=100 * 1000 * 1000,
          help="max size of log files before rollover",
      )
      options.define(
          "log_file_num_backups",
          type=int,
          default=10,
          help="number of log files to keep",
      )
  
      options.define(
          "log_rotate_when",
          type=str,
          default="midnight",
          help=(
              "specify the type of TimedRotatingFileHandler interval "
              "other options:('S', 'M', 'H', 'D', 'W0'-'W6')"
          ),
      )
      options.define(
          "log_rotate_interval",
          type=int,
          default=1,
          help="The interval value of timed rotating",
      )
  
      options.define(
          "log_rotate_mode",
          type=str,
          default="size",
          help="The mode of rotating files(time or size)",
      )
  
      options.add_parse_callback(lambda: enable_pretty_logging(options))
  
file_path: catboost/contrib/python/tornado/tornado-4/tornado/log.py
imports: from __future__ import absolute_import, division, print_function
  import logging
  import logging.handlers
  import sys
  from tornado.escape import _unicode
  from tornado.util import unicode_type, basestring_type
label_desc: Use image node_id 4 for calling a global function with example usage: define_logging_options(options) without return types