How to use the @tsed/core.isClass function in @tsed/core

it("should return false (obj)", () => {
      expect(isClass(Object)).to.eq(false);
    });

it("should return false (arrow function)", () => {
      expect(isClass(() => {})).to.eq(false);
    });

it("should return false (date)", () => {
      expect(isClass(new Date())).to.eq(false);
    });

private static createJsonSchema(schema: JsonSchema = new JsonSchema(), type: any, collectionType?: any): JsonSchema {
    if (isClass(type)) {
      schema = Object.keys(schema.toObject()).reduce((newSchema: any, key: string) => {
        if (!(key === "type" || key === "items" || key === "additionalProperties")) {
          newSchema[key] = schema[key];
        }

        return newSchema;
      }, JsonSchema.ref(type));
    } else {
      schema.type = type;
    }

    if (collectionType) {
      schema.toCollection(collectionType);
    }

    return schema!;

set useClass(value: Type) {
    if (isClass(value)) {
      this._useClass = getClass(value);
      this._store = Store.from(value);
    }
  }

async function resolveSymbols(item: any, excludes: string[]) {
  if (isClass(item)) {
    return await [item];
  }

  return importFiles(item, excludes);
}

        .filter(symbol => isClass(symbol))
        .forEach(symbol => {

static throwInjectorError(token: any, currentDependency: any, error: any) {
    if (currentDependency && isClass(token)) {
      error.message = printDependencyInjectionError(token, {...currentDependency, message: error.message});
    }

    throw new InjectionError(token, error);
  }
}

        .filter(token => isClass(token) && GlobalProviders.has(token))!;
    } catch (er) {