Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing

      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing

      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing

      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing

Validações genéricas e metadados:

* `alias`
* `title`
* `description`
* `deprecated`

Validações específicas para textos:

* `min_length`
* `max_length`
* `regex`

Nesses exemplos você viu como declarar validações em valores do tipo `str`.

* O cliente não tem direitos para realizar aquela operação.
* O cliente não tem acesso aquele recurso.
* O item que o cliente está tentando acessar não existe.
* etc.


Nesses casos, você normalmente retornaria um **HTTP status code** próximo ao status code na faixa do status code **400** (do 400 ao 499).

      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing

      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing

* Compartilhar conexões com banco de dados.
* Aplicar regras de segurança, autenticação, papéis de usuários, etc.
* E muitas outras coisas...

Tudo isso, enquanto minimizamos a repetição de código.

## Primeiros passos

Vamos ver um exemplo simples. Tão simples que não será muito útil, por enquanto.

Mas dessa forma podemos focar em como o sistema de **Injeção de Dependência** funciona.

### Criando uma dependência, ou "injetável"

to use the Work (including but not limited to damages for loss of goodwill, 
work stoppage, computer failure or malfunction, or any and all other 
commercial damages or losses), even if such Contributor has been advised of 
the possibility of such damages. 

9. Accepting Warranty or Additional Liability. While redistributing the Work