code: function subscribe(object, callback, context) {
      if (object && object[_emberMetalStreamsStream.IS_STREAM]) {
        return object.subscribe(callback, context);
      }
    }
docs: /*
  A method of subscribing to a stream which is safe for use with a non-stream
  object. If a non-stream object is passed, the function does nothing.
  
  @public
  @for Ember.stream
  @function subscribe
  @param {Object|Stream} object Object or stream to potentially subscribe to.
  @param {Function} callback Function to run when stream value changes.
  @param {Object} [context] the callback will be executed with this context if it
  is provided.