This is because we also have another variable named `router` in the submodule `users`.

If we had imported one after the other, like:

```Python
from .routers.items import router
from .routers.users import router
```

the `router` from `users` would overwrite the one from `items` and we wouldn't be able to use them at the same time.

So, to be able to use both of them in the same file, we import the submodules directly:

Import `File` and `UploadFile` from `fastapi`:

{* ../../docs_src/request_files/tutorial001_an_py39.py hl[3] *}

## Define `File` Parameters { #define-file-parameters }

Create file parameters the same way you would for `Body` or `Form`:

{* ../../docs_src/request_files/tutorial001_an_py39.py hl[9] *}

/// info

`File` is a class that inherits directly from `Form`.

            to.ansiHash = from.ansiHash != null ? Arrays.copyOf(from.ansiHash, from.ansiHash.length) : null;
            to.unicodeHash = from.unicodeHash != null ? Arrays.copyOf(from.unicodeHash, from.unicodeHash.length) : null;
        } else {
            NtlmPasswordAuthenticator.cloneInternal(to, from);
        }
    }

    /**
     * Compares two {@code NtlmPasswordAuthentication} objects for

///

### What is "Mounting" { #what-is-mounting }

"Mounting" means adding a complete "independent" application in a specific path, that then takes care of handling all the sub-paths.

With this, we get tooling support, from editors and mypy as this code is correct in terms of types, but we also get the data filtering from FastAPI.

How does this work? Let's check that out. 🤓

### Type Annotations and Tooling { #type-annotations-and-tooling }

First let's see how editors, mypy and other tools would see this.

$ python main.py

// As we didn't set the env var, we get the default value

Hello World from Python

// But if we create an environment variable first
$ export MY_NAME="Wade Wilson"

// And then call the program again
$ python main.py

// Now it can read the environment variable

Hello Wade Wilson from Python
```

</div>

////

//// tab | Windows PowerShell

<div class="termy">

## Description from docstring { #description-from-docstring }

As descriptions tend to be long and cover multiple lines, you can declare the *path operation* description in the function <abbr title="a multi-line string as the first expression inside a function (not assigned to any variable) used for documentation">docstring</abbr> and **FastAPI** will read it from there.

        }
        // Can't map from a raw class to anything other than itself or a wildcard.
        // You can't say "assuming String is Integer".
        // And we don't support "assuming String is T"; user has to say "assuming T is String".
        throw new IllegalArgumentException("No type mapping from " + fromClass + " to " + to);
      }
    }.visit(from);
  }

  /**

```

/// note | Technical Details

You could also use `from starlette.requests import Request` and `from starlette.responses import JSONResponse`.

**FastAPI** provides the same `starlette.responses` as `fastapi.responses` just as a convenience for you, the developer. But most of the available responses come directly from Starlette. The same with `Request`.

///

For example, if the **application server** is only receiving communication from the trusted **proxy**, you can set it to `--forwarded-allow-ips="*"` to make it trust all incoming IPs, as it will only receive requests from whatever is the IP used by the **proxy**.