How to use the @lumino/collections.BPlusTree function in @lumino/collections

static create(options: Datastore.IOptions): Datastore {
    let {schemas} = options;
    // Throws an error for invalid schemas:
    Private.validateSchemas(schemas);

    let context =  {
      inTransaction: false,
      transactionId: '',
      version: 0,
      storeId: options.id,
      change: {},
      patch: {},
    };

    let tables = new BPlusTree>(Private.recordCmp);
    if (options.restoreState) {
      // If passed state to restore, pass the intital state to recreate each
      // table
      let state = JSON.parse(options.restoreState);
      tables.assign(map(schemas, s => {
        return Table.recreate(s, context, state[s.id] || []);
      }));
    } else {
      // Otherwise, simply create a new, empty table
      tables.assign(map(schemas, s => {
        return Table.create(s, context);
      }));
    }

    return new Datastore(context, tables, options.adapter);
  }

* Construct a new datastore table.
   *
   * @param schema - The schema for the table.
   *
   * @param context - The datastore context.
   */
  private constructor(schema: S, context: Datastore.Context, records?: IterableOrArrayLike>) {
    this.schema = schema;
    this._context = context;
    if (records) {
      this._records.assign(records);
    }
  }

  private _context: Datastore.Context;
  private _records = new BPlusTree>(Private.recordCmp);
}


/**
 * The namespace for the `Table` class statics.
 */
export
namespace Table {
  /**
   * A type alias for the table update type.
   */
  export
  type Update<s> = {
    readonly [recordId: string]: Record.Update<s>;
  };
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