old_contents: const os = require('os');
  
  /**
   * Get macOS version of current system
   *
   * @param {number} [darwinRelease] darwin version
   * @returns {string| undefined} macOS version or undefined if other platform
   * @example
   * const {macOSVersion} = require('get-osx-version');
   *
   * console.log('macOS version: ' + macOSVersion());
   */
  module.exports.macOSVersion = (darwinRelease) => {
  	/* istanbul ignore next */
  	if (typeof darwinRelease === 'undefined' && process.platform === 'darwin') {
  		darwinRelease = Number.parseFloat(os.release());
  	} else if (typeof darwinRelease === 'undefined') {
  		return;
  	}
  
  	switch (darwinRelease) {
  		case 1.3:
  			return '10.0';
  		case 1.4:
  		case 5.1:
  		case 5.2:
  		case 5.3:
  		case 5.4:
  		case 5.5:
  			return '10.1';
  		default:
  			return '10.' + (Number.parseFloat(darwinRelease) - 4).toFixed(1);
  	}
  }
  
new_contents: const os = require('os');
  
  /**
   * Get macOS version of current system
   *
   * @param {number} [darwinRelease] darwin version
   * @returns {string| undefined} macOS version or undefined if other platform
   * @example
   * const {macOSVersion} = require('get-osx-version');
   *
   * console.log('macOS version: ' + macOSVersion());
   */
  module.exports.macOSVersion = darwinRelease => {
  	/* istanbul ignore next */
  	if (typeof darwinRelease === 'undefined' && process.platform === 'darwin') {
  		darwinRelease = Number.parseFloat(os.release());
  	} else if (typeof darwinRelease === 'undefined') {
  		return;
  	}
  
  	switch (darwinRelease) {
  		case 1.3:
  			return '10.0';
  		case 1.4:
  		case 5.1:
  		case 5.2:
  		case 5.3:
  		case 5.4:
  		case 5.5:
  			return '10.1';
  		default:
  			return '10.' + (Number.parseFloat(darwinRelease) - 4).toFixed(1);
  	}
  };
  
subject: fix lint issues