public async Task AddAndRemove()
{
LCObject parent = new LCObject("Parent");
LCObject c1 = new LCObject("Child");
parent.AddRelation("children", c1);
LCObject c2 = new LCObject("Child");
parent.AddRelation("children", c2);
await parent.Save();
LCRelation <LCObject> relation = parent["children"] as LCRelation <LCObject>;
LCQuery <LCObject> query = relation.Query;
int count = await query.Count();
TestContext.WriteLine($"count: {count}");
Assert.AreEqual(count, 2);
parent.RemoveRelation("children", c2);
await parent.Save();
int count2 = await query.Count();
TestContext.WriteLine($"count: {count2}");
Assert.AreEqual(count2, 1);
}