Cannot setup network layer to handle subscriptions using example from docs. Relay 12

When following the example on how to set up the network layer to handle subscriptions from the [docs site](https://relay.dev/docs/guided-tour/updating-data/graphql-subscriptions/#configuring-the-network-layer) I am receiving multiple errors trying to set up the network layer in a `create-react-app` app initialized in typescript.

The first Error I get is.
```
TS2345: Argument of type 'Observable>' is not assignable to parameter of type 'ObservableFromValue>'.
Type 'Observable>' is not assignable to type 'Subscribable>'.
The types returned by 'subscribe(...)' are incompatible between these types.
Property 'closed' is missing in type '{ unsubscribe: () => void; }' but required in type 'Subscription'.
42 | });
43 |
> 44 | return Observable.from(subscribeObservable);
| ^^^^^^^^^^^^^^^^^^^
45 | };
```
I was able to solve this issue by changing
```ts
const subscribe = (request: { text: any; name: any }, variables: any) => {
const subscribeObservable = subscriptionClient.request({
query: request.text,
operationName: request.name,
variables,
});

return Observable.from(subscribeObservable);
};
```
to
```ts
const subscribe = (request: { text: any; name: any }, variables: any) => {
const subscribeObservable = subscriptionClient
.request({
query: request.text,
operationName: request.name,
variables,
})
.subscribe({
next: (data: any) => {
console.log(data);
},
error: (error: any) => {
console.log(error);
},
complete: () => {
console.log("complete");
},
});

return Observable.from(subscribeObservable);
};
```
And now the issue I am getting is:
```
TS2345: Argument of type '(request: { text: any; name: any;}, variables: any) => Observable<{ unsubscribe: () => void; }>' is not assignable to parameter of type 'SubscribeFunction'.
Type 'RelayObservable<{ unsubscribe: () => void; }>' is not assignable to type 'RelayObservable | Disposable'.
Type 'RelayObservable<{ unsubscribe: () => void; }>' is not assignable to type 'RelayObservable'.
Type '{ unsubscribe: () => void; }' is not assignable to type 'GraphQLResponse'.
Type '{ unsubscribe: () => void; }' is missing the following properties from type 'readonly GraphQLSingularResponse[]': length, concat, join, slice, and 18 more.
58 |
59 | const environment = new Environment({
> 60 | network: Network.create(fetchQuery, subscribe),
| ^^^^^^^^^
61 | store: new Store(new RecordSource()),
62 | });
```

Below are the contents of the file where I am trying to set up the network layer.

```ts
import {
Environment,
Network,
RecordSource,
RequestParameters,
Store,
Variables,
Observable,
} from "relay-runtime";

import { SubscriptionClient } from "subscriptions-transport-ws";

async function fetchQuery(operation: RequestParameters, variables: Variables) {
const response = await fetch(
process.env.REACT_APP_GRAPHQL_URL || "http://localhost:8080/api/query",
{
method: "POST",
headers: {
"Content-Type": "application/json",
},
body: JSON.stringify({
query: operation.text,
variables,
}),
}
);
return await response.json();
}

const websocketURL =
process.env.REACT_APP_GRAPHQL_URL || "ws://localhost:8080/api/query";

const subscriptionClient = new SubscriptionClient(websocketURL, {
reconnect: true,
});

const subscribe = (request: { text: any; name: any }, variables: any) => {
const subscribeObservable = subscriptionClient
.request({
query: request.text,
operationName: request.name,
variables,
})
.subscribe({
next: (data: any) => {
console.log(data);
},
error: (error: any) => {
console.log(error);
},
complete: () => {
console.log("complete");
},
});

return Observable.from(subscribeObservable);
};

const environment = new Environment({
network: Network.create(fetchQuery, subscribe),
store: new Store(new RecordSource()),
});

export default environment;
```

Start with the network-layer subscription example at the linked Relay documentation page and reproduce it in the TypeScript create-react-app setup shown in the issue. Trace the Observable and Network.create types behind the reported errors; done means the documented example type-checks and configures subscriptions without the shown TypeScript failures.

Written by the indexing model from the issue text.