Hay una variable de entorno **especial** llamada **`PATH`** que es utilizada por los sistemas operativos (Linux, macOS, Windows) para encontrar programas a ejecutar.

El valor de la variable `PATH` es un string largo que consiste en directorios separados por dos puntos `:` en Linux y macOS, y por punto y coma `;` en Windows.

Por ejemplo, la variable de entorno `PATH` podría verse así:

//// tab | Linux, macOS

        self.remaining_points = remaining
        self.reset_at = datetime.fromisoformat(reset_at.replace("Z", "+00:00"))


rate_limiter = RateLimiter()


discussions_query = """
query Q($after: String, $category_id: ID) {
  repository(name: "fastapi", owner: "fastapi") {
    discussions(first: 30, after: $after, categoryId: $category_id) {
      edges {
        cursor
        node {
          number

    "groups" : [ {
      "testProject" : "largeJavaMultiProjectNoBuildSrc",
      "coverage" : {
        "per_day" : [ "linux" ]
      }
    } ]
  }, {
    "testId" : "org.gradle.performance.regression.java.JavaConfigurationCachePerformanceTest.assemble storing configuration cache state with hot daemon",
    "groups" : [ {

Another big feature needed by APIs is data validation, making sure that the data is valid, given certain parameters. For example, that some field is an `int`, and not some random string. This is especially useful for incoming data.

   *
   * <p>This method is not atomic: the map may not be empty after returning if there were concurrent
   * writes.
   */
  public void clear() {
    map.clear();
  }

  @Override
  public String toString() {
    return map.toString();
  }

  /*
   * ConcurrentMap operations which we may eventually add.
   *

Because the editor knows the types of the variables, you don't only get completion, you also get error checks:

<img src="/img/python-types/image04.png">

Now you know that you have to fix it, convert `age` to a string with `str(age)`:

{* ../../docs_src/python_types/tutorial004_py310.py hl[2] *}

## Declaring types { #declaring-types }

You just saw the main place to declare type hints. As function parameters.

            "type": "type_error.integer"
        }
    ]
}
```

다음과 같은 텍스트 버전을 받게 됩니다:

```
Validation errors:
Field: ('path', 'item_id'), Error: Input should be a valid integer, unable to parse string as an integer
```

### `HTTPException` 오류 핸들러 오버라이드하기 { #override-the-httpexception-error-handler }

같은 방식으로 `HTTPException` 핸들러도 오버라이드할 수 있습니다.

예를 들어, 이런 오류들에 대해 JSON 대신 일반 텍스트 응답을 반환하고 싶을 수 있습니다:

      <span style="background-color:#007166"><font color="#D3D7CF"> app </font></span>  Using import string: <font color="#3465A4">main:app</font>

   <span style="background-color:#007166"><font color="#D3D7CF"> server </font></span>  Server started at <font color="#729FCF"><u style="text-decoration-style:solid">http://0.0.0.0:8000</u></font>

          acquireShared(-1);
        }
        return doCompletion;
      }
    }

    static CancellationException cancellationExceptionWithCause(
        @Nullable String message, @Nullable Throwable cause) {
      CancellationException exception = new CancellationException(message);
      exception.initCause(cause);
      return exception;
    }
  }

Puedes personalizar esa función. Toma un `APIRoute` y retorna un string.

Por ejemplo, aquí está usando el primer tag (probablemente tendrás solo un tag) y el nombre de la *path operation* (el nombre de la función).