om/node_modules/path-key/index.js

'use strict';
module.exports = opts => {
	opts = opts || {};

	const env = opts.env || process.env;
	const platform = opts.platform || process.platform;

	if (platform !== 'win32') {
		return 'PATH';
	}

	return Object.keys(env).find(x => x.toUpperCase() === 'PATH') || 'Path';
};