if al {
			t := nat(nil).shl(y.mant, uint(ey-ex))
			z.mant = t.sub(x.mant, t)
		} else {
			z.mant = z.mant.shl(y.mant, uint(ey-ex))
			z.mant = z.mant.sub(x.mant, z.mant)
		}
	default:
		// ex == ey, no shift needed
		z.mant = z.mant.sub(x.mant, y.mant)
	case ex > ey:
		if al {
			t := nat(nil).shl(x.mant, uint(ex-ey))
			z.mant = t.sub(t, y.mant)
		} else {
			z.mant = z.mant.shl(x.mant, uint(ex-ey))

                                                   ty), node)
      else:
        raise NotImplementedError('USub type not recognized: ' + str(ty))
      return ssa_value, ty
    raise NotImplementedError('USub operator not recognized')

  def visit_For(self, node):
    raise NotImplementedError('For operator not recognized')

  def visit_While(self, node):

	// FSUB <Sd>, <Sn>, <Sm>
	{0xffe0fc00, 0x1e203800, FSUB, instArgs{arg_Sd, arg_Sn, arg_Sm}, nil},
	// FSUB <Dd>, <Dn>, <Dm>
	{0xffe0fc00, 0x1e603800, FSUB, instArgs{arg_Dd, arg_Dn, arg_Dm}, nil},
	// FSUB <Vd>.<t>, <Vn>.<t>, <Vm>.<t>

# 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"

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

=== "Python 3.10+"

    ```Python hl_lines="8-9"
    {!> ../../../docs_src/dependencies/tutorial005_an_py310.py!}
    ```

=== "Python 3.9+"

下图显示的是主应用 API 文档，只包括其自有的*路径操作*。

<img src="/img/tutorial/sub-applications/image01.png">

然后查看子应用文档 <a href="http://127.0.0.1:8000/subapi/docs" class="external-link" target="_blank">http://127.0.0.1:8000/subapi/docs。</a>

下图显示的是子应用的 API 文档，也是只包括其自有的*路径操作*，所有这些路径操作都在 `/subapi` 子路径前缀下。

<img src="/img/tutorial/sub-applications/image02.png">

两个用户界面都可以正常运行，因为浏览器能够与每个指定的应用或子应用会话。

### 技术细节：`root_path`

)

// A SubFS is a file system with a Sub method.
type SubFS interface {
	FS

	// Sub returns an FS corresponding to the subtree rooted at dir.
	Sub(dir string) (FS, error)
}

// Sub returns an [FS] corresponding to the subtree rooted at fsys's dir.
//
// If dir is ".", Sub returns fsys unchanged.
// Otherwise, if fs implements [SubFS], Sub returns fsys.Sub(dir).
// Otherwise, Sub returns a new [FS] implementation sub that,

(F(MADD|NMADD|MSUB|NMSUB)S neg:(FNEGS x) y z) && neg.Uses == 1 => (F(NMSUB|MSUB|NMADD|MADD)S x y z)
(F(MADD|NMADD|MSUB|NMSUB)S x y neg:(FNEGS z)) && neg.Uses == 1 => (F(MSUB|NMSUB|MADD|NMADD)S x y z)
(F(MADD|NMADD|MSUB|NMSUB)D neg:(FNEGD x) y z) && neg.Uses == 1 => (F(NMSUB|MSUB|NMADD|MADD)D x y z)

			if (!cret)
			{
				if (!(flags & REG_NOSUB) && nsub < 0 && *ans == '(')
				{
					for (p = ans; *p; p++)
						if (*p == '(')
							nsub++;
						else if (*p == '{')
							nsub--;
					if (nsub >= 0)
					{
						if (test & TEST_IGNORE_OVER)
						{
							if (nmatch > nsub)
								nmatch = nsub + 1;
						}
						else if (nsub != preg.re_nsub)
						{

LeeeeT <******@****.***> 1680341164 +0300

<img src="/img/tutorial/sub-applications/image01.png">

و سپس اسناد زیر برنامه را در آدرس <a href="http://127.0.0.1:8000/subapi/docs" class="external-link" target="_blank">http://127.0.0.1:8000/subapi/docs</a>. باز کنید.

اسناد API خودکار برای زیر برنامه را خواهید دید، که فقط شامل path operations خود می شود، همه در زیر مسیر `/subapi` قرار دارند:

<img src="/img/tutorial/sub-applications/image02.png">