source: imaps-frontend/node_modules/is-symbol/index.js

'use strict';

var toStr = Object.prototype.toString;
var hasSymbols = require('has-symbols')();

if (hasSymbols) {
        var symToStr = Symbol.prototype.toString;
        var symStringRegex = /^Symbol\(.*\)$/;
        var isSymbolObject = function isRealSymbolObject(value) {
                if (typeof value.valueOf() !== 'symbol') {
                        return false;
                }
                return symStringRegex.test(symToStr.call(value));
        };

        module.exports = function isSymbol(value) {
                if (typeof value === 'symbol') {
                        return true;
                }
                if (toStr.call(value) !== '[object Symbol]') {
                        return false;
                }
                try {
                        return isSymbolObject(value);
                } catch (e) {
                        return false;
                }
        };
} else {

        module.exports = function isSymbol(value) {
                // this environment does not support Symbols.
                return false && value;
        };
}