text: import { FETCH_WEATHER } from '../actions/index.js';
  
  export default function(state = [], action) {
    switch (action.type) {
      case FETCH_WEATHER:
        // Not mutating state, but rather returning a new instance of it - concat adds on to existing - same with ... 
        return [ action.payload.data, ...state ]; 
        // Inserts new data at top of state
    }
    return state;
  }