block12.js

// server/src/resolvers.js
const {
  ...,
  // here we reference the startSession function we have just created
  videoApi: { joinSession, startSession },
} = require('./graphql');
...
const resolvers = {
  ...
  Mutation: {
    ...
    // here we assign that function as the resolver for the startVideocallSession mutation
    startVideocallSession: startSession,
    ...
  },
};