when I do insert_one operation with object `

{"key": "1" * 1024 * 1024 * 16}

`

I will get an error like:

```
pymongo.errors.WriteError: object to insert too large. size in bytes: 16777248, max size: 16777216
```

then I doinsert_one with `

{"key": "1" * 1024 * 1024 * 18}

`

I will get:

```
pymongo.errors.DocumentTooLarge: BSON document too large (18874451 bytes) - the connected server supports BSON document sizes up to 16793598 bytes.
```

I mean, There are two Exceptions with one situation( document is too large). That seems strange.

and there is a similar case on insert_many.

when I set a big document as `doc1`, and do `insert_many([doc1, {}])`, I will get `pymongo.errors.DocumentTooLarge`. That seems ok. but when I do `insert_many([{}, doc1])`, I did get `pymongo.errors.AutoReconnect`.

Then I read the source code of pymongo. I do know what is going on now. I just think, could it be better when I meet one kind of situation, I will get only one exception.