docs: def get_policy_definitions(settings):
      """Find all multiauth policy definitions from the settings dict.
  
      This function processes the paster deployment settings looking for items
      that start with "multiauth.policy.<policyname>.".  It pulls them all out
      into a dict indexed by the policy name.
      """
      policy_definitions = {}
      for name in settings:
          if not name.startswith("multiauth.policy."):
              continue
          value = settings[name]
          name = name[len("multiauth.policy."):]
          policy_name, setting_name = name.split(".", 1)
          if policy_name not in policy_definitions:
              policy_definitions[policy_name] = {}
          policy_definitions[policy_name][setting_name] = value
      return policy_definitions