Fragment Subscriptions - subscribeTo Extension Approach

subscribeTo_extension.graphql

fragment userFragment on User
subscribeTo(userAvatarChangeSubscription)
{
  name
  username
  avatarUrl(size: 200)
  avatarChangeId # can be an implicit field on this fragment added by
                 # the server to track subscription events on the client
}

subscription userAvatarChangeSubscription {
  userAvatarChange # somehow linked to the previous fragment,
                   # for each occurrence of the previous fragment in its query
  {
    avatarUrl(size: 200)
  }
}