code: function createGetter({ key, namespace, normalizedMappings, vmIdentifierKey, instanceIdentifierKey, stateKey }) {
      return function() {
          // find the state object
          const state = namespace
              ? resolveObjectPath(this.$store.state, namespace, '/')
              : this.$store.state;
  
          // find our container of instances
          const instancesContainer = resolveObjectPath(state, stateKey, '.');
  
          // find our instance within it
          const instance = instancesContainer.find(obj => obj[instanceIdentifierKey] === this[vmIdentifierKey]);
  
          // and if all goes well, resolve the piece of state we're looking for
          if (instance) {
              return typeof normalizedMappings[key] === 'function'
                  ? normalizedMappings[key](instance)
                  : resolveObjectPath(instance, normalizedMappings[key]);
          }
      }
  }
docs: create a getter for a particular piece of state