## 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

First, create the main, top-level, **FastAPI** application, and its *path operations*:

```Python hl_lines="3  6-8"
{!../../docs_src/sub_applications/tutorial001.py!}
```

		return "", false
	}

	// Check if path expression ends in a key
	jpath := operand.Left.Left.Primary.JPathExpr
	n := len(jpath.PathExpr)
	if n > 0 && jpath.PathExpr[n-1].Key == nil {
		return "", false
	}
	ps := jpath.String()
	if idx := strings.LastIndex(ps, "."); idx >= 0 {
		// Get last part of path string.
		ps = ps[idx+1:]
	}
	return ps, true
}

func IsLikelyMountPoint(path string) bool {
	path = filepath.Dir(path)
	if v, ok := mountPointCache.Load(path); ok {
		return v.(bool)
	}
	wpath, _ := windows.UTF16PtrFromString(path)
	wvolume := make([]uint16, len(path)+1)

	if err := windows.GetVolumePathName(wpath, &wvolume[0], uint32(len(wvolume))); err != nil {
		mountPointCache.Store(path, false)
		return false
	}

Sebastián Ramírez <******@****.***> 1728247014 +0200

	// Check if new heal sequence to be started overlaps with any
	// existing, running sequence
	hpath := pathJoin(h.bucket, h.object)
	for k, hSeq := range ahs.healSeqMap {
		if !hSeq.hasEnded() && (HasPrefix(k, hpath) || HasPrefix(hpath, k)) {
			errMsg = "The provided heal sequence path overlaps with an existing " +
				fmt.Sprintf("heal path: %s", k)
			return nil, errorCodes.ToAPIErr(ErrHealOverlappingPaths), errMsg
		}
	}

Sebastián Ramírez <******@****.***> 1728247014 +0200

Sebastián Ramírez <******@****.***> 1728247014 +0200

Sebastián Ramírez <******@****.***> 1728247014 +0200

Sebastián Ramírez <******@****.***> 1728247014 +0200

Sebastián Ramírez <******@****.***> 1728247014 +0200