old_contents: # -*- coding: utf-8 -*-
  ''' Default configuration for the application
  
  This data must be supplemented with custom configuration to which
  URL_SHORTENER_CONFIGURATION environment variable points, overriding
  some of the values specified here.
  
  :var SQLALCHEMY_DATABASE_URI: uri of database to be used by the application.
  
  The default value serves only as documentation, and it was taken from:
  http://docs.sqlalchemy.org/en/latest/core/engines.html#database-urls
  
  :var MIN_NEW_ALIAS_LENGTH: a minimum number of characters in a newly
  generated alias
  :var MAX_NEW_ALIAS_LENGTH: a maximum number of characters in a newly
  generated alias
  :var SECRET_KEY: a secret key to be used by the application
  :var LOG_FILE: a name of file to which the application writes logs.
  :var REGISTRATION_RETRY_LIMIT: a maximum number of retries for
  registering a new shortened url
  :var GOOGLE_SAFE_BROWSING_API_KEY: a value necessary for querying
  Google Safe Browsing API.
  :var HOST_BLACKLIST_FILE: a name of file storing blacklisted hosts
  (hostnames and ip addresses). Each line must contain one host.
  '''
  SQLALCHEMY_DATABASE_URI = (
      'dialect+driver://username:password@host:port/database'
  )
  MIN_NEW_ALIAS_LENGTH = 1
  MAX_NEW_ALIAS_LENGTH = 4
  SECRET_KEY = 'a secret key'
  LOG_FILE = None
  REGISTRATION_RETRY_LIMIT = 10
  GOOGLE_SAFE_BROWSING_API_KEY = 'a key'
  HOST_BLACKLIST_FILE = None
  
new_contents: # -*- coding: utf-8 -*-
  ''' Default configuration for the application
  
  This data must be supplemented with custom configuration to which
  URL_SHORTENER_CONFIGURATION environment variable points, overriding
  some of the values specified here.
  
  :var SQLALCHEMY_DATABASE_URI: uri of database to be used by the application.
  
  The default value serves only as documentation, and it was taken from:
  http://docs.sqlalchemy.org/en/latest/core/engines.html#database-urls
  
  :var MIN_NEW_ALIAS_LENGTH: a minimum number of characters in a newly
  generated alias
  :var MAX_NEW_ALIAS_LENGTH: a maximum number of characters in a newly
  generated alias
  :var SECRET_KEY: a secret key to be used by the application
  :var LOG_FILE: a name of file to which the application writes logs.
  The value can be None, in which case the application won't write logs
  to any file.
  
  If the value is set, it must consist of an existing directory (if any),
  but the file doesn't have to exist. The application uses timed roating
  file handler with interval of one day, so the file specified here will
  be created (if it doesn't exist yet) and used for one day. After that,
  it will be renamed, and another file with the same name will be created
  in the same directory and used.
  
  :var REGISTRATION_RETRY_LIMIT: a maximum number of retries for
  registering a new shortened url
  :var GOOGLE_SAFE_BROWSING_API_KEY: a value necessary for querying
  Google Safe Browsing API.
  :var HOST_BLACKLIST_FILE: a name of file storing blacklisted hosts
  (hostnames and ip addresses). Each line must contain one host.
  '''
  SQLALCHEMY_DATABASE_URI = (
      'dialect+driver://username:password@host:port/database'
  )
  MIN_NEW_ALIAS_LENGTH = 1
  MAX_NEW_ALIAS_LENGTH = 4
  SECRET_KEY = 'a secret key'
  LOG_FILE = None
  REGISTRATION_RETRY_LIMIT = 10
  GOOGLE_SAFE_BROWSING_API_KEY = 'a key'
  HOST_BLACKLIST_FILE = None
  
subject: Update default_config docstring on LOG_FILE