And your **FastAPI** application might also be composed of several files/modules, etc.

### **FastAPI** app file { #fastapi-app-file }

Let's say you have a file structure as described in [Bigger Applications](bigger-applications.md){.internal-link target=_blank}:

```
.
├── app
│   ├── __init__.py
│   └── main.py
```

In the file `main.py` you have your **FastAPI** app:

/**
 * Filter interface for SMB file filtering.
 *
 * This interface allows selective filtering of files
 * when listing directory contents in SMB shares.
 */
public interface SmbFileFilter {

    /**
     * Tests whether the specified SMB file should be included in a file list.
     *
     * @param file the SMB file to test for inclusion
     * @return whether the given file should be included

#
# The properties defined in this file will be made available through
# user properties at the very beginning of Maven's boot process.
#

# Comma-separated list of files to include.
# Each item may be enclosed in quotes to gracefully include spaces. Items are trimmed before being loaded.
# If the first character of an item is a question mark, the load will silently fail if the file does not exist.

- Secure File Transfer Protocol (SFTP) – Defined by the Internet Engineering Task Force (IETF) as an
  extended version of SSH 2.0, allowing file transfer over SSH and for use with Transport Layer
  Security (TLS) and VPN applications.

- File Transfer Protocol over SSL/TLS (FTPS) – Encrypted FTP communication via TLS certificates.

    }

    /**
     * Checks if a file exists at the specified path within the servlet context.
     *
     * @param path the file path relative to the servlet context
     * @return true if the file exists, false otherwise
     */
    public static boolean fileExists(final String path) {
        final File file = new File(LaServletContextUtil.getServletContext().getRealPath(path));

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

		}
		seen[name] = true
		return nil
	})
	if err != nil {
		log.Fatal(err)
	}
	if err := zw.Close(); err != nil {
		log.Fatal(err)
	}
	if len(seen) == 0 {
		log.Fatalf("did not find any files to add")
	}
	if !seen["US/Eastern"] {
		log.Fatalf("did not find US/Eastern to add")
	}
	if err := os.WriteFile(args[0], zb.Bytes(), 0666); err != nil {
		log.Fatal(err)
	}

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

else
  PROFILE_JSON_PATH="$TFCI_OUTPUT_DIR/profile.json.gz"
fi

# TODO(b/361369076) Remove the following block after TF NumPy 1 is dropped
# Move hermetic requirement lock files for NumPy 1 to the root
if [[ "$TFCI_WHL_NUMPY_VERSION" == 1 ]]; then
  cp ./ci/official/requirements_updater/numpy1_requirements/*.txt .
fi

if [[ $TFCI_PYCPP_SWAP_TO_BUILD_ENABLE == 1 ]]; then

It will also **download** files for other packages that FastAPI depends on.

Then it will **extract** all those files and put them in a directory in your computer.

By default, it will put those files downloaded and extracted in the directory that comes with your Python installation, that's the **global environment**.