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。

如果没有提供默认值，默认为 `None`，此处我们提供了 `"World"` 作为要使用的默认值。

///

然后，您可以调用该 Python 程序：

<div class="termy">

import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.DoNotCall;
import java.util.ListIterator;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A list iterator that does not support {@link #remove}, {@link #add}, or {@link #set}.
 *
 * @since 7.0
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

    }

    deflatedBytes.writeAll(buffer)
    deflatedBytes.writeInt(OCTETS_TO_ADD_BEFORE_INFLATION)

    val totalBytesToRead = inflater.bytesRead + deflatedBytes.size

    // We cannot read all, as the source does not close.
    // Instead, we ensure that all bytes from source have been processed by inflater.
    do {
      inflaterSource.readOrInflate(buffer, Long.MAX_VALUE)

    Our workaround is to tell GWT that util.concurrent and all other packages
    have prod supersource, even if they have none. GWT is happy to ignore us
    when we specify a nonexistent path.

    (I hope that this workaround does not cause its own problems in the future.)
-->
<super-source path="super"/>

<inherits name="com.google.common.annotations.Annotations" />
<inherits name="com.google.gwt.core.Core" />

```Python hl_lines="4  21"
{!> ../../docs_src/encoder/tutorial001_py310.py!}
```

////

👉 🖼, ⚫️ 🔜 🗜 Pydantic 🏷 `dict`, & `datetime` `str`.

🏁 🤙 ⚫️ 🕳 👈 💪 🗜 ⏮️ 🐍 🐩 <a href="https://docs.python.org/3/library/json.html#json.dumps" class="external-link" target="_blank">`json.dumps()`</a>.

⚫️ 🚫 📨 ⭕ `str` ⚗ 💽 🎻 📁 (🎻). ⚫️ 📨 🐍 🐩 💽 📊 (✅ `dict`) ⏮️ 💲 &amp; 🎧-💲 👈 🌐 🔗 ⏮️ 🎻.

/// note

		line: 1,
		file: file,
	}
}

// We want center dot (·) and division slash (∕) to work as identifier characters.
func isIdentRune(ch rune, i int) bool {
	if unicode.IsLetter(ch) {
		return true
	}
	switch ch {
	case '_': // Underscore; traditional.
		return true
	case '\u00B7': // Represents the period in runtime.exit. U+00B7 '·' middle dot
		return true

			// case 9, vs route to multiple hosts
			args: strings.Split("service productpage", " "),
			expectedOutput: `Service: productpage
DestinationRule: productpage for "productpage"
   WARNING POD DOES NOT MATCH ANY SUBSETS.  (Non matching subsets v1)
   Matching subsets: 
      (Non-matching subsets v1)
   No Traffic Policy
VirtualService: bookinfo
   Route to host "productpage" with weight 30%

 */
@GwtCompatible
@FunctionalInterface
@ElementTypesAreNonnullByDefault
public interface RemovalListener<K, V> {
  /**
   * Notifies the listener that a removal occurred at some point in the past.
   *
   * <p>This does not always signify that the key is now absent from the cache, as it may have
   * already been re-added.
   */
  // Technically should accept RemovalNotification<? extends K, ? extends V>, but because

     * dependency properties.
     *
     * @return if the artifact can be added to the class path
     *
     * @deprecated A value of {@code true} does not mean that the dependency should
     * be placed on the classpath. See {@code JavaPathType} instead for better analysis.
     */
    @Deprecated
    boolean isAddedToClasspath();

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package gradlebuild.docs

import org.w3c.dom.Document
import org.w3c.dom.Element
import org.w3c.dom.Node
import org.w3c.dom.NodeList

class DomBuilder extends BuilderSupport {
    Document document
    Node parent