code: function addDoc(array = [], action) {
    const { meta, payload } = action;
    if (!meta.subcollections || meta.storeAs) {
      return [
        ...array.slice(0, payload.ordered.newIndex),
        { id: meta.doc, ...payload.data },
        ...array.slice(payload.ordered.newIndex),
      ];
    }
  
    // Add doc to subcollection by modifying the existing doc at this level
    return modifyDoc(array, action);
  }
docs: Case reducer for adding a document to a collection or subcollection.
  @param {Array} [array=[]] - Redux state of current collection
  @param {Object} action - The action that was dispatched
  @return {Array} State with document modified