How to use the ngrx-forms.formGroupReducer function in ngrx-forms

export function formStateReducer(
  s = INITIAL_STATE,
  a: CreateGroupElementAction | RemoveGroupElementAction,
) {
  s = formGroupReducer(s, a);

  switch (a.type) {
    case CreateGroupElementAction.TYPE:
      return updateGroup({
        group: group => {
          const newGroup = addGroupControl(group, a.name, false);

          // alternatively we can also use setValue
          // const newValue = { ...group.value, [a.name]: false };
          // const newGroup = setValue(group, newValue);

          return newGroup;
        },
      })(s);

    case RemoveGroupElementAction.TYPE:

formState(s = INITIAL_STATE, a: Action) {
    return formGroupReducer(s, a);
  },
});

formState(fs = INITIAL_FORM_STATE, a: Action) {
    return formGroupReducer(fs, a);
  },
});

formState(s = INITIAL_STATE, a: Action) {
    return formGroupReducer(s, a);
  },
  submittedValue(s: FormValue | undefined, a: SetSubmittedValueAction) {

formState(s = INITIAL_STATE, a: Action) {
    return validateAndUpdateForm(formGroupReducer(s, a));
  },
  submittedValue(s: FormValue | undefined, a: SetSubmittedValueAction) {

export function formStateReducer(state = INITIAL_STATE, a: BlockUIAction | UnblockUIAction) {
  state = formGroupReducer(state, a);

  switch (a.type) {
    case BlockUIAction.TYPE: {
      state = updateRecursive(
        state,
        s => setUserDefinedProperty(s, 'wasDisabled', s.isDisabled),
      );
      return disable(state);
    }

    case UnblockUIAction.TYPE: {
      state = enable(state);
      return updateRecursive(
        state,
        s => s.userDefinedProperties.wasDisabled ? disable(s) : s,
      );

formState(s = INITIAL_STATE, a: Action) {
    return formGroupReducer(s, a);
  },
});

export function reducer(fs: FormGroupState = INITIAL_FORM_STATE, a: Action) {
  return formGroupReducer(fs, a);
}

formState(s = INITIAL_STATE, a: Action) {
    return formGroupReducer(s, a);
  },
});