* Und die Datei `app/internal/admin.py` ist ein weiteres Submodul: `app.internal.admin`.

<img src="/img/tutorial/bigger-applications/package.svg">

Die gleiche Dateistruktur mit Kommentaren:

```
.
├── app                  # „app“ ist ein Python-Package
│   ├── __init__.py      # diese Datei macht „app“ zu einem „Python-Package“

# Bigger Applications - Multiple Files

If you are building an application or a web API, it's rarely the case that you can put everything on a single file.

**FastAPI** provides a convenience tool to structure your application while keeping all the flexibility.

!!! info
    If you come from Flask, this would be the equivalent of Flask's Blueprints.

## An example file structure

Let's say you have a file structure like this:

```
.
├── app

* 📤 📁 `app/internal/` ⏮️ ➕1️⃣ 📁 `__init__.py`, ⚫️ ➕1️⃣ "🐍 📦": `app.internal`.
*  & 📁 `app/internal/admin.py` ➕1️⃣ 🔁: `app.internal.admin`.

<img src="/img/tutorial/bigger-applications/package.svg">

🎏 📁 📊 ⏮️ 🏤:

```
.
├── app                  # "app" is a Python package
│   ├── __init__.py      # this file makes "app" a "Python package"

* 还有一个子目录 `app/internal/` 包含另一个 `__init__.py` 文件，因此它是又一个「Python 子包」：`app.internal`。
* `app/internal/admin.py` 是另一个子模块：`app.internal.admin`。

<img src="https://fastapi.tiangolo.com/img/tutorial/bigger-applications/package.svg">

带有注释的同一文件结构：

```
.
├── app                  # 「app」是一个 Python 包
│   ├── __init__.py      # 这个文件使「app」成为一个 Python 包
│   ├── main.py          # 「main」模块，例如 import app.main

			if err != nil {
				return nil, err
			}
			todo -= primes[i].BitLen()
		}

		// Make sure that primes is pairwise unequal.
		for i, prime := range primes {
			for j := 0; j < i; j++ {
				if prime.Cmp(primes[j]) == 0 {
					continue NextSetOfPrimes
				}
			}
		}

		n := new(big.Int).Set(bigOne)
		totient := new(big.Int).Set(bigOne)
		pminus1 := new(big.Int)
		for _, prime := range primes {

	var val, pos int
	var digLen int // number of digits in current octet
	s := in[off:end]
	for i := 0; i < len(s); i++ {
		if s[i] >= '0' && s[i] <= '9' {
			if digLen == 1 && val == 0 {
				return parseAddrError{in: in, msg: "IPv4 field has octet with leading zero"}
			}
			val = val*10 + int(s[i]) - '0'
			digLen++
			if val > 255 {

	var _p0 uint32
	if disableAllPrivileges {
		_p0 = 1
	}
	r0, _, e1 := syscall.Syscall6(procAdjustTokenPrivileges.Addr(), 6, uintptr(token), uintptr(_p0), uintptr(unsafe.Pointer(newstate)), uintptr(buflen), uintptr(unsafe.Pointer(prevstate)), uintptr(unsafe.Pointer(returnlen)))

	// that the lsb of mant corresponds to 1/2 ulp for the precision of
	// x (i.e., for mant we want x.prec + 1 bits).
	mant := nat(nil).set(x.mant)
	exp := int(x.exp) - mant.bitLen()
	s := mant.bitLen() - int(x.prec+1)
	switch {
	case s < 0:
		mant = mant.shl(mant, uint(-s))
	case s > 0:
		mant = mant.shr(mant, uint(+s))
	}
	exp += s
	// x = mant * 2**exp with lsb(mant) == 1/2 ulp of x.prec

func (k *PrivateKey) ECDH() (*ecdh.PrivateKey, error) {
	c := curveToECDH(k.Curve)
	if c == nil {
		return nil, errors.New("ecdsa: unsupported curve by crypto/ecdh")
	}
	size := (k.Curve.Params().N.BitLen() + 7) / 8
	if k.D.BitLen() > size*8 {
		return nil, errors.New("ecdsa: invalid private key")
	}
	return c.NewPrivateKey(k.D.FillBytes(make([]byte, size)))
}

func curveToECDH(c elliptic.Curve) ecdh.Curve {
	switch c {

	m.nat = NewNat().setBig(n)
	m.leading = _W - bitLen(m.nat.limbs[len(m.nat.limbs)-1])
	m.m0inv = minusInverseModW(m.nat.limbs[0])
	m.rr = rr(m)
	return m, nil
}

// bitLen is a version of bits.Len that only leaks the bit length of n, but not
// its value. bits.Len and bits.LeadingZeros use a lookup table for the
// low-order bits on some architectures.
func bitLen(n uint) int {
	var len int