let changedEmployees =
          (action, category, employeeFunc) =>
            category.employees.map((employee) => {
              if (employee.name !== action.employee.name) {
                return employee;
              }

              return employeeFunc(employee);
            });

        let changedEmployeeCategories =
          (action, state, employeeFunc, categoryFunc) =>
            state.categories.map((category) => {
              if (category.name !== action.employee.category) {
                return category;
              }

              let newEmployees = changedEmployees(action, category, employeeFunc);
              return categoryFunc(category, newEmployees);
            });

        let changedEmployeeState =
          (state, action, employeeFunc, categoryFunc, stateFunc) => {
            let newCategories = changedEmployeeCategories(action, state, employeeFunc, categoryFunc);
            return stateFunc(state, newCategories);
          };