code: function setNestingLevel(config, dir, rawValue) {
      // config can have value "0", so we can't use "!config[dir]"
      if ( !(dir in config) ) {
          config[dir] = Math.max(parseInt(rawValue, 10) || 0, 0);
      }
  }
docs: Parse and set nesting level in config object
  @param {object} config Nesting level config
  @param {string} dir Path to directory
  @param {string} rawValue Raw value from config (.borschik)