var global = require('../internals/global'); var isCallable = require('../internals/is-callable'); var wellKnownSymbol = require('../internals/well-known-symbol'); var $$OBSERVABLE = wellKnownSymbol('observable'); var NativeObservable = global.Observable; var NativeObservablePrototype = NativeObservable && NativeObservable.prototype; module.exports = !isCallable(NativeObservable) || !isCallable(NativeObservable.from) || !isCallable(NativeObservable.of) || !isCallable(NativeObservablePrototype.subscribe) || !isCallable(NativeObservablePrototype[$$OBSERVABLE]);