Structurally identical to React Router's RouterContext<T>, so a key created
by this package and a key created by createContext<T>() from react-router
are interchangeable. defaultValue is returned by get() when no value has
been set; a key without one makes get() throw for an unset key.
A React Router context key, used by identity as the argument to
RouterLoadContext.get/RouterLoadContext.set.Structurally identical to React Router's
RouterContext<T>, so a key created by this package and a key created bycreateContext<T>()fromreact-routerare interchangeable.defaultValueis returned byget()when no value has been set; a key without one makesget()throw for an unset key.Since
0.2.0