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">

lit==17.0.6 \
    --hash=sha256:dfa9af9b55fc4509a56be7bf2346f079d7f4a242d583b9f2e0b078fd0abae31b
    # via -r ci/official/requirements_updater/requirements.in
markdown==3.8 \
    --hash=sha256:794a929b79c5af141ef5ab0f2f642d0f7b1872981250230e72682346f7cc90dc \
    --hash=sha256:7df81e63f0df5c4b24b7d156eb81e4690595239b7d70937d0409f1b0de319c6f
    # via tb-nightly
markdown-it-py==3.0.0 \

lit==17.0.6 \
    --hash=sha256:dfa9af9b55fc4509a56be7bf2346f079d7f4a242d583b9f2e0b078fd0abae31b
    # via -r ci/official/requirements_updater/requirements.in
markdown==3.8 \
    --hash=sha256:794a929b79c5af141ef5ab0f2f642d0f7b1872981250230e72682346f7cc90dc \
    --hash=sha256:7df81e63f0df5c4b24b7d156eb81e4690595239b7d70937d0409f1b0de319c6f
    # via tb-nightly
markdown-it-py==3.0.0 \

lit==17.0.6 \
    --hash=sha256:dfa9af9b55fc4509a56be7bf2346f079d7f4a242d583b9f2e0b078fd0abae31b
    # via -r ci/official/requirements_updater/requirements.in
markdown==3.8 \
    --hash=sha256:794a929b79c5af141ef5ab0f2f642d0f7b1872981250230e72682346f7cc90dc \
    --hash=sha256:7df81e63f0df5c4b24b7d156eb81e4690595239b7d70937d0409f1b0de319c6f
    # via tb-nightly
markdown-it-py==3.0.0 \

.call(n.default(ot),"toggle")})),n.default(document).on("keyup",lt,(function(e){return 38==e.keyCode?(e.preventDefault(),void n.default(ft).children().last().focus()):40==e.keyCode?(e.preventDefault(),void n.default(ft).children().first().focus()):void setTimeout((function(){ht._jQueryInterface.call(n.default(ot),"search")}),100)})),n.default(document).on("keydown",ft,(function(e){var t=n.default(":focus");38==e.keyCode&&(e.preventDefault(),t.is(":first-child")?t.siblings().last().focus():t.prev...

        int ctxOffset = 144;

        // Preauth integrity context
        SMBUtil.writeInt2(PreauthIntegrityNegotiateContext.NEGO_CTX_PREAUTH_TYPE, buffer, ctxOffset);
        SMBUtil.writeInt2(38, buffer, ctxOffset + 2); // Data length
        ctxOffset += 8; // Skip reserved

        // Hash algorithm count and salt length
        SMBUtil.writeInt2(1, buffer, ctxOffset);

pkg debug/dwarf, const TagClassType = 2
pkg debug/dwarf, const TagCommonDwarfBlock = 26
pkg debug/dwarf, const TagCommonInclusion = 27
pkg debug/dwarf, const TagCompileUnit = 17
pkg debug/dwarf, const TagConstType = 38
pkg debug/dwarf, const TagConstant = 39
pkg debug/dwarf, const TagDwarfProcedure = 54
pkg debug/dwarf, const TagEntryPoint = 3
pkg debug/dwarf, const TagEnumerationType = 4
pkg debug/dwarf, const TagEnumerator = 40

lit==17.0.6 \
    --hash=sha256:dfa9af9b55fc4509a56be7bf2346f079d7f4a242d583b9f2e0b078fd0abae31b
    # via -r ci/official/requirements_updater/requirements.in
markdown==3.8 \
    --hash=sha256:794a929b79c5af141ef5ab0f2f642d0f7b1872981250230e72682346f7cc90dc \
    --hash=sha256:7df81e63f0df5c4b24b7d156eb81e4690595239b7d70937d0409f1b0de319c6f
    # via tb-nightly
markdown-it-py==3.0.0 \

		37: {
			IsTruncated: false,
			Objects: []ObjectInfo{
				{Name: "foo/201910/1112"},
				{Name: "foo/201910/1122"},
			},
		},
		// ListObjectsResult-38 list with prefix match 1 level deep
		38: {
			IsTruncated: false,
			Objects: []ObjectInfo{
				{Name: "foo/201910/1112"},
				{Name: "foo/201910/1122"},
				{Name: "foo/201910/2112"},
				{Name: "foo/201910_txt"},
			},

lit==17.0.6 \
    --hash=sha256:dfa9af9b55fc4509a56be7bf2346f079d7f4a242d583b9f2e0b078fd0abae31b
    # via -r ci/official/requirements_updater/requirements.in
markdown==3.8 \
    --hash=sha256:794a929b79c5af141ef5ab0f2f642d0f7b1872981250230e72682346f7cc90dc \
    --hash=sha256:7df81e63f0df5c4b24b7d156eb81e4690595239b7d70937d0409f1b0de319c6f
    # via tb-nightly
markdown-it-py==3.0.0 \