Member predicate Redux::DelegatingReducer::getStateHandlerArg

Gets a data flow node holding a reducer to which handling of state.prop is delegated.

For example, gets the fn in combineReducers({foo: fn}) with prop bound to foo.

The delegating reducer should behave as a function of this form:

function outer(state, action) {
  return {
    prop: inner(state.prop, action),
    ...
  }
}