l`: A URL to the target host. This URL supports Server Variables
                and MAY be relative, to indicate that the host location is relative
                to the location where the OpenAPI document is being served. Variable
                substitutions will be made when a variable is named in `{`brackets`}`.
                * `description`: An optional string describing the host designated by
                the URL. [CommonMark syntax](https://commonmark.org/) MAY be used for
                rich text representation.
                * `variables`: A `dict` between a variable name and its value. The value
                    is used for substitution in the server's URL template.

                Read more in the
                [FastAPI docs for Behind a Proxy](https://fastapi.tiangolo.com/advanced/behind-a-proxy/#additional-servers).

                **Example**

                ```python
                from fastapi import FastAPI

                app = FastAPI(
                    servers=[
                        {"url": "https://stag.example.com", "description": "Staging environment"},
                        {"url": "https://prod.example.com", "description": "Production environment"},
                    ]
                )
                ```
                rA