## Mounting a **FastAPI** application { #mounting-a-fastapi-application }

"Mounting" means adding a completely "independent" application in a specific path, that then takes care of handling everything under that path, with the _path operations_ declared in that sub-application.

### Top-level application { #top-level-application }

# Sub-dependencies { #sub-dependencies }

You can create dependencies that have **sub-dependencies**.

They can be as **deep** as you need them to be.

**FastAPI** will take care of solving them.

## First dependency "dependable" { #first-dependency-dependable }

You could create a first dependency ("dependable") like:

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}

It doesn't matter for **FastAPI**. It will detect the parameters by their names, types and default declarations (`Query`, `Path`, etc), it doesn't care about the order.

So, you can declare your function as:

{* ../../docs_src/path_params_numeric_validations/tutorial002_py39.py hl[7] *}

     <span style="background-color:#007166"><font color="#D3D7CF"> INFO </font></span>  Uvicorn running on <font color="#729FCF"><u style="text-decoration-style:solid">http://127.0.0.1:8000</u></font> <b>(</b>Press CTRL+C
             to quit<b>)</b>
     <span style="background-color:#007166"><font color="#D3D7CF"> INFO </font></span>  Started reloader process <b>[</b><font color="#34E2E2"><b>383138</b></font><b>]</b> using WatchFiles

But then you have to call "that method that converts the first letter to upper case".

Was it `upper`? Was it `uppercase`? `first_uppercase`? `capitalize`?

Then, you try with the old programmer's friend, editor autocompletion.

You type the first parameter of the function, `first_name`, then a dot (`.`) and then hit `Ctrl+Space` to trigger the completion.

But, sadly, you get nothing useful:

{* ../../docs_src/settings/app03_an_py39/main.py hl[1,11] *}

Then for any subsequent call of `get_settings()` in the dependencies for the next requests, instead of executing the internal code of `get_settings()` and creating a new `Settings` object, it will return the same object that was returned on the first call, again and again.

#### `lru_cache` Technical Details { #lru-cache-technical-details }

        if self.call is None:
            return False  # pragma: no cover
        if inspect.isgeneratorfunction(
            _impartial(self.call)
        ) or inspect.isgeneratorfunction(_unwrapped_call(self.call)):
            return True
        if inspect.isclass(_unwrapped_call(self.call)):
            return False
        dunder_call = getattr(_impartial(self.call), "__call__", None)  # noqa: B004

        newCapacity = Integer.MAX_VALUE; // guaranteed to be >= newCapacity
      }
      return newCapacity;
    }

    /**
     * Returns a new immutable array. The builder can continue to be used after this call, to append
     * more values and build again.
     *
     * <p><b>Performance note:</b> the returned array is backed by the same array as the builder, so

        sub_dependant.call = cast(Callable[..., Any], sub_dependant.call)
        call = sub_dependant.call
        use_sub_dependant = sub_dependant
        if (
            dependency_overrides_provider
            and dependency_overrides_provider.dependency_overrides
        ):
            original_call = sub_dependant.call
            call = getattr(

///

## Other Asynchronous Function Calls { #other-asynchronous-function-calls }

As the testing function is now asynchronous, you can now also call (and `await`) other `async` functions apart from sending requests to your FastAPI application in your tests, exactly as you would call them anywhere else in your code.

/// tip