status can be obtained and has been tinkering with for a long time. Do not know how to call mutations, getters and actions defined in the module?
    const mA = {
      state : {
        a : 1,
        b : 1,
      },
      //  mutations
      mutations : {
        add : state =>{
          state.aPP
        },
      },
      getters : {
        double : state=> {
          return state.a *2
        }
      }
    }
    const mB = {
      state : {
        a : 2,
        b : 2,
      },
      //  mutations
      mutations: {
        addB: state => {
          state.aPP
        },
      },
      //  actions
      actions : {
        asyncAdd : ({commit, rootState ,state}) =>{
          setTimeout(() => {
            commit("add");
          }, 1000);
        }
      }
    }
    const store = new Vuex.Store({
      modules : {
        a : mA,
        b : mB,
      }
    });
    console.log(store.state.a);
						