!important;\n    display: inline-flex !important;\n  }\n}\n\n@media print {\n  .d-print-none {\n    display: none !important;\n  }\n  .d-print-inline {\n    display: inline !important;\n  }\n  .d-print-inline-block {\n    display: inline-block !important;\n  }\n  .d-print-block {\n    display: block !important;\n  }\n  .d-print-table {\n    display: table !important;\n  }\n  .d-print-table-row {\n    display: table-row !important;\n  }\n  .d-print-table-cell {\n    display: table-cell !important;\n  }\n  .d-print-flex...

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

Под капотом" open("./somefile.txt") создаёт объект называемый "контекстным менеджером".

Когда блок `with` завершается, он обязательно закрывает файл, даже если были исключения.

// explicitly by running a TPUReplicatedOutput operation on the parallel device.
//
// TODO(allenl): There are some use-cases that are only supported by copying to
// host at the moment (e.g. debug print on a tensor, .numpy(), etc.). We either
// need to return something here or address these use-cases one by one.
TFE_TensorHandle* CopyTensorFromParallelDevice(TFE_Context* context,

		for idx, d := range v {
			if idx > 0 {
				writer.WriteByte(',')
			}
			stmt.DB.Dialector.QuoteTo(writer, d)
		}
		writer.WriteByte(')')
	default:
		stmt.DB.Dialector.QuoteTo(writer, fmt.Sprint(field))
	}
}

// Quote returns quoted value
func (stmt *Statement) Quote(field interface{}) string {
	var builder strings.Builder
	stmt.QuoteTo(&builder, field)
	return builder.String()
}

!important;\n    display: inline-flex !important;\n  }\n}\n\n@media print {\n  .d-print-none {\n    display: none !important;\n  }\n  .d-print-inline {\n    display: inline !important;\n  }\n  .d-print-inline-block {\n    display: inline-block !important;\n  }\n  .d-print-block {\n    display: block !important;\n  }\n  .d-print-table {\n    display: table !important;\n  }\n  .d-print-table-row {\n    display: table-row !important;\n  }\n  .d-print-table-cell {\n    display: table-cell !important;\n  }\n  .d-print-flex...

    long t0 = System.nanoTime();
    try {
      super.runTest();
    } finally {
      long elapsedMillis = (System.nanoTime() - t0) / (1000L * 1000L);
      if (elapsedMillis >= profileThreshold)
        System.out.printf("%n%s: %d%n", toString(), elapsedMillis);
    }
  }

  //     /**
  //      * Runs all JSR166 unit tests using junit.textui.TestRunner
  //      */
  //     public static void main(String[] args) {

デフォルトの例外ハンドラを`fastapi.exception_handlers`からインポートして再利用することができます:

```Python hl_lines="2 3 4 5 15 21"
{!../../docs_src/handling_errors/tutorial006.py!}
```

この例では、非常に表現力のあるメッセージでエラーを`print`しています。

////

### 在 Python 中读取环境变量

您还可以在 Python 之外的地方（例如终端中或使用任何其他方法）创建环境变量，然后在 Python 中读取它们。

例如，您可以有一个名为 `main.py` 的文件，其中包含以下内容：

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip

<a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> 的第二个参数是要返回的默认值。

        @Override
        public String getAsString(final Object value) {
            if (value instanceof Date) {
                return DEFAULT_DATE_PRINTER.print(((Date) value).getTime());
            }
            return null;
        }

        @Override
        public Object getAsObject(final String value) {
            if (StringUtil.isEmpty(value)) {

                    }
                }
                buf.append('}');
                buf.append('\n');
                try {
                    response.getWriter().print(buf.toString());
                } catch (final IOException e) {
                    throw new IORuntimeException(e);
                }
                return true;
            }, OptionalThing.empty());