Returns a store with entities cleared out.

Returns a new MapGraphStore for the given parameters:

• :id-fn A function that will be passed an entity and should return a unique value that will be used as a reference to that entity. Defaults to :id.
• :entities A map of stored entities. Defaults to {}.
• :cache-redirects A map of of field to function, that redirects the root from whence the selection-set will be resolved. Defaults to {}.
• :cache-key The default generic key for the store’s cache. Defaults to :artemis.stores.mapgrah.core/cache.

This store requires that every entity meant to normalize for a GraphQL query resolves a unique value when called against the store’s :id-fn.

Returns true if store is a mapgraph store.