How to use the @vue/composition-api.inject function in @vue/composition-api

setup: () => {
    const fromMount = inject('fromMount')
    const setInSetup = ref('created')

    return {
      fromMount,
      setInSetup
    }
  }
})

export const useNotifications = () => inject(key)

export function useApolloClient (clientId: string = null) {
  const providedApolloClients: { [key: string]: ApolloClient } = inject(ApolloClients, null)
  const providedApolloClient: ApolloClient = inject(DefaultApolloClient, null)

  function resolveClient (clientId: string = null): ApolloClient {
    let resolvedClient
    if (clientId) {
      if (!providedApolloClients) {
        throw new Error(`No apolloClients injection found, tried to resolve '${clientId}' clientId`)
      }
      resolvedClient = providedApolloClients[clientId]
    } else {
      clientId = 'default'
      if (providedApolloClients) {
        resolvedClient = providedApolloClients.default
      } else {
        resolvedClient = providedApolloClient
      }
    }

setup () {
    const required = inject('required')

    return {
      required
    }
  }
}

export const useStore = () => inject(key) as Hook

export function useApolloClient (clientId: string = null) {
  const providedApolloClients: { [key: string]: ApolloClient } = inject(ApolloClients, null)
  const providedApolloClient: ApolloClient = inject(DefaultApolloClient, null)

  function resolveClient (clientId: string = null): ApolloClient {
    let resolvedClient
    if (clientId) {
      if (!providedApolloClients) {
        throw new Error(`No apolloClients injection found, tried to resolve '${clientId}' clientId`)
      }
      resolvedClient = providedApolloClients[clientId]
    } else {
      clientId = 'default'
      if (providedApolloClients) {
        resolvedClient = providedApolloClients.default
      } else {
        resolvedClient = providedApolloClient
      }