*
 * The first element on each line is a single hex code point (like 0041) or a hex code point range
 * (like 0030..0039).
 *
 * The second element on each line is a mapping type, like `valid` or `mapped`.
 *
 * For lines that contain a mapping target, the next thing is a sequence of hex code points (like
 * 0031 2044 0034).
 *
 * All other data is ignored.
 */

    assertThat(stringPrep("\u2029")).isNull()
    assertThat(stringPrep("\ud834\udd7a")).isNull() // Note that this is one code point.
  }

  @Test fun prohibitionPrivateUse() {
    assertThat(stringPrep("\uf8ff")).isNull()
    assertThat(stringPrep("\udbff\udffd")).isNull() // Note that this is one code point.
  }

  @Test fun prohibitionNonCharacter() {
    assertThat(stringPrep("\ufdd0")).isNull()

* Hooks (Before/After Create/Save/Update/Delete/Find)
* Eager loading with `Preload`, `Joins`
* Transactions, Nested Transactions, Save Point, RollbackTo to Saved Point
* Context, Prepared Statement Mode, DryRun Mode
* Batch Insert, FindInBatches, Find To Map
* SQL Builder, Upsert, Locking, Optimizer/Index/Comment Hints, NamedArg, Search/Update/Create with SQL Expr

//
// Examples:
//
// - 1.5 will be serialized as "1500m"
// - 1.5Gi will be serialized as "1536Mi"
//
// Note that the quantity will NEVER be internally represented by a
// floating point number. That is the whole point of this exercise.
//
// Non-canonical values will still parse as long as they are well formed,
// but will be re-emitted in their canonical form. (So always use canonical
// form, or don't diff.)
//

  )
}

/**
 * If [mapping] qualifies to be encoded as [MappedRange.InlineDelta] return new instance, otherwise null.
 * An [MappedRange.InlineDelta] must be a mapping from a single code-point to a single code-point with a difference
 * that can be represented in 2^18-1.
 */
internal fun inlineDeltaOrNull(mapping: Mapping): MappedRange.InlineDelta? {
  if (mapping.hasSingleSourceCodePoint) {

    // appendCodePoint(). The Punycode algorithm processes code points in increasing code-point
    // order, not in increasing index order.
    val codePoints = mutableListOf<Int>()

    // consume all code points before the last delimiter (if there is one)
    //  and copy them to output, fail on any non-basic code point
    val lastDelimiter = string.lastIndexOf('-', limit)
    if (lastDelimiter >= pos) {

   * For example, the tags in this schema are 0 and 1:
   *
   * ```
   * Point ::= SEQUENCE {
   *   x [0] INTEGER OPTIONAL,
   *   y [1] INTEGER OPTIONAL
   * }
   * ```
   *
   * You may also specify a tag class like [DerHeader.TAG_CLASS_APPLICATION]. The default tag class
   * is [DerHeader.TAG_CLASS_CONTEXT_SPECIFIC].
   *
   * ```
   * Point ::= SEQUENCE {
   *   x [APPLICATION 0] INTEGER OPTIONAL,

I have been avoiding the creation of a new framework for several years. First I tried to solve all the features covered by **FastAPI** using many different frameworks, plug-ins, and tools.

!!! tip
    When writing the code to document a callback, it might be useful to imagine that you are that *external developer*. And that you are currently implementing the *external API*, not *your API*.

    Temporarily adopting this point of view (of the *external developer*) can help you feel like it's more obvious where to put the parameters, the Pydantic model for the body, for the response, etc. for that *external API*.

### Create a callback `APIRouter`

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