<img src="/img/tutorial/dependencies/image02.png">

## Shortcut

But you see that we are having some code repetition here, writing `CommonQueryParams` twice:

=== "Python 3.8+"

    ```Python
    commons: Annotated[CommonQueryParams, Depends(CommonQueryParams)]

They take a `set` of `str` with the name of the attributes to include (omitting the rest) or to exclude (including the rest).

This can be used as a quick shortcut if you have only one Pydantic model and want to remove some data from the output.

!!! tip
    But it is still recommended to use the ideas above, using multiple classes, instead of these parameters.

Using `Optional[str]` instead of just `str` will let the editor help you detecting errors where you could be assuming that a value is always a `str`, when it could actually be `None` too.

`Optional[Something]` is actually a shortcut for `Union[Something, None]`, they are equivalent.

This also means that in Python 3.10, you can use `Something | None`:

=== "Python 3.10+"

    ```Python hl_lines="1"

  // pair) is hashed and the hash value is used to shuffle the list
  // of queues and deal a hand of the size specified here.  The
  // request is put into one of the shortest queues in that hand.
  // `handSize` must be no larger than `queues`, and should be
  // significantly smaller (so that a few heavy flows do not
  // saturate most of the queues).  See the user-facing

  // pair) is hashed and the hash value is used to shuffle the list
  // of queues and deal a hand of the size specified here.  The
  // request is put into one of the shortest queues in that hand.
  // `handSize` must be no larger than `queues`, and should be
  // significantly smaller (so that a few heavy flows do not
  // saturate most of the queues).  See the user-facing

  // pair) is hashed and the hash value is used to shuffle the list
  // of queues and deal a hand of the size specified here.  The
  // request is put into one of the shortest queues in that hand.
  // `handSize` must be no larger than `queues`, and should be
  // significantly smaller (so that a few heavy flows do not
  // saturate most of the queues).  See the user-facing

  // pair) is hashed and the hash value is used to shuffle the list
  // of queues and deal a hand of the size specified here.  The
  // request is put into one of the shortest queues in that hand.
  // `handSize` must be no larger than `queues`, and should be
  // significantly smaller (so that a few heavy flows do not
  // saturate most of the queues).  See the user-facing