Trying to understand the new React 16.3 createContext source code

createContextWat.js

/**
 * This file: https://github.com/facebook/react/blob/fb85cf2e9c52a4b2999144a89a6ee8256aec55c7/packages/react/src/ReactContext.js
 * if you remove the <flow> stuff and the "calculate changed bits" stuff, it appears to be
 * a function that, when called, returns an object literal with some weird circular references?
 *
 * How is this working / what am I missing here?
 */
export function createContext(defaultValue) {
  const context = {
    $$typeof: REACT_CONTEXT_TYPE,
    defaultValue,
    currentValue: defaultValue,
    // These are circular
    Provider: (null: any),
    Consumer: (null: any),
  };

  context.Provider = {
    $$typeof: REACT_PROVIDER_TYPE,
    context,
  };
  context.Consumer = context;

  return context;
}